diff --git a/dev-assets/guidebook/Makefile b/dev-assets/guidebook/Makefile
deleted file mode 100644
index 95ca53b..0000000
--- a/dev-assets/guidebook/Makefile
+++ /dev/null
@@ -1,16 +0,0 @@
-SHELL := /bin/bash
-
-# `make serve` to serve the mkdocs site on localhost.
-.PHONY: serve
-serve:
-	mkdocs serve
-
-# `make build` to build the static documentation site.
-.PHONY: build
-build:
-	mkdocs build
-
-# `make clean` cleans everything up.
-.PHONY: clean
-clean:
-	rm -rf site
diff --git a/dev-assets/guidebook/build.py b/dev-assets/guidebook/build.py
deleted file mode 100644
index d3789fd..0000000
--- a/dev-assets/guidebook/build.py
+++ /dev/null
@@ -1,73 +0,0 @@
-#!/usr/bin/env python3
-
-import codecs
-import glob
-import os
-import markdown
-import jinja2
-import re
-
-def main():
-    if not os.path.isdir("./compiled"):
-        print("Make output directory: ./compiled")
-        os.mkdir("./compiled")
-        os.mkdir("./compiled/pages")
-
-    # Render the main index.html template.
-    with codecs.open("./pages/index.html", "r", "utf-8") as fh:
-        html = fh.read()
-        html = render_template(html)
-        with open("./compiled/index.html", "w") as outfh:
-            outfh.write(html)
-
-    # Load the Markdown wrapper HTML template.
-    html_wrapper = "$CONTENT"
-    with codecs.open("./pages/markdown.html", "r", "utf-8") as fh:
-        html_wrapper = fh.read()
-
-    for md in glob.glob("./pages/*.md"):
-        filename = md.split(os.path.sep)[-1]
-        htmlname = filename.replace(".md", ".html")
-        print("Compile Markdown: {} -> {}".format(filename, htmlname))
-
-        with codecs.open(md, 'r', 'utf-8') as fh:
-            data = fh.read()
-            rendered = markdown.markdown(data,
-                extensions=["codehilite", "fenced_code"],
-            )
-            html = html_wrapper.replace("$CONTENT", rendered)
-            html = render_template(html,
-                title=title_from_markdown(data),
-            )
-
-            with open(os.path.join("compiled", "pages", htmlname), "w") as outfh:
-                outfh.write(html)
-
-jinja_env = jinja2.Environment()
-
-def render_template(input, *args, **kwargs):
-    templ = jinja_env.from_string(input)
-    return templ.render(
-        app_name="Project: Doodle",
-        app_version=get_app_version(),
-        *args, **kwargs
-    )
-
-def title_from_markdown(text):
-    """Retrieve the title from the first Markdown header."""
-    for line in text.split("\n"):
-        if line.startswith("# "):
-            return line[2:]
-
-def get_app_version():
-    """Get the app version from pkg/branding/branding.go in Doodle"""
-    ver = re.compile(r'Version\s*=\s*"(.+?)"')
-    with codecs.open("../../pkg/branding/branding.go", "r", "utf-8") as fh:
-        text = fh.read()
-        for line in text.split("\n"):
-            m = ver.search(line)
-            if m:
-                return m[1]
-
-if __name__ == "__main__":
-    main()
diff --git a/dev-assets/guidebook/build.sh b/dev-assets/guidebook/build.sh
deleted file mode 100755
index 11d620b..0000000
--- a/dev-assets/guidebook/build.sh
+++ /dev/null
@@ -1,16 +0,0 @@
-#!/bin/bash
-
-if [[ ! -d "./venv" ]]; then
-	echo Creating Python virtualenv...
-	python3 -m venv ./venv
-	source ./venv/bin/activate
-	pip install -r requirements.txt
-else
-	source ./venv/bin/activate
-fi
-
-python build.py
-
-# Copy static files in.
-mkdir -p compiled/pages/res
-cp -r pages/res/*.* compiled/pages/res/
diff --git a/dev-assets/guidebook/docs/about.md b/dev-assets/guidebook/docs/about.md
deleted file mode 100644
index e501178..0000000
--- a/dev-assets/guidebook/docs/about.md
+++ /dev/null
@@ -1,3 +0,0 @@
-# About Project: Doodle
-
-Lorem ipsum.
diff --git a/dev-assets/guidebook/docs/custom-doodads/edit-external.md b/dev-assets/guidebook/docs/custom-doodads/edit-external.md
deleted file mode 100644
index 3e253ff..0000000
--- a/dev-assets/guidebook/docs/custom-doodads/edit-external.md
+++ /dev/null
@@ -1,20 +0,0 @@
-# Drawing Doodads in an External Program
-
-Doodad sprites can be drawn using any image editor and saved as .png files
-(with transparency). You can then create a doodad file from your series of
-PNG images.
-
-Most of the built-in doodads that ship with the game were created in this way.
-
-## Create a Doodad from Images
-
-Save each frame of your doodad as a separate PNG image and then use the `doodad`
-command-line tool to convert them to a `.doodad` file.
-
-```bash
-# Usage:
-doodad convert [options] <inputs.png> <output.doodad>
-
-# Example:
-doodad convert door-closed.png door-open.png door.doodad
-```
diff --git a/dev-assets/guidebook/docs/custom-doodads/edit-in-game.md b/dev-assets/guidebook/docs/custom-doodads/edit-in-game.md
deleted file mode 100644
index f26901e..0000000
--- a/dev-assets/guidebook/docs/custom-doodads/edit-in-game.md
+++ /dev/null
@@ -1,27 +0,0 @@
-# Drawing a Doodad In-Game
-
-Project: Doodle has some **limited** support to draw your doodad sprites
-in-game. Currently you can only draw one frame (image) for the doodad
-and save it to disk.
-
-To start a new doodad, open the game and enter the level editor.
-
-Select the "New Doodad" button at the top of the screen to start drawing a
-new doodad. Choose the size (square) of its sprite when prompted.
-
-Doodads saved in-game go in your user config directory for the game. On Linux,
-this is at ~/.config/doodle.
-
-If you want to create a doodad with multiple frames (to animate it or have
-varying states that change the doodad's appearance in the level), the
-`doodad` tool is recommended. See
-[drawing images in an external program](edit-external.md).
-
-## Future Planned Features
-
-Creating doodads in-game is intended to be a fully supported feature. The
-following features are planned to be supported:
-
-* Support editing multiple frames instead of only the first frame.
-* Implement some features only available on the `doodad` tool using in-game
-  UI, such as attaching JavaScripts to the doodad.
diff --git a/dev-assets/guidebook/docs/custom-doodads/index.md b/dev-assets/guidebook/docs/custom-doodads/index.md
deleted file mode 100644
index 67fa6fc..0000000
--- a/dev-assets/guidebook/docs/custom-doodads/index.md
+++ /dev/null
@@ -1,43 +0,0 @@
-# Creating Custom Doodads
-
-Project: Doodle is designed to be modder friendly and provides tools to help
-you create your own custom doodads to use in your levels.
-
-You can draw the sprites for the doodad either in-game or using an external
-image editor. Then, you can program their logic using JavaScript to make them
-"do" stuff in-game and interact with the player and other doodads.
-
-* Drawing your Doodad's Sprites
-    * [In-Game](edit-in-game.md)
-    * [In an External Program](edit-external.md)
-* Program its Behavior
-    * [JavaScript](scripts.md)
-
-## doodad (Command Line Tool)
-
-Your copy of the game should have shipped with a `doodad` command-line tool
-bundled with it. On Windows it's called `doodad.exe` and should be in the same
-folder as the game executable. On Mac OS, it is inside the .app bundle.
-
-The `doodad` tool provides a command-line interface to create and inspect
-doodad and level files from the game. You'll need to use this tool, at the very
-least, to attach a JavaScript to your doodad to make it "do" stuff in-game.
-
-You can create a doodad from PNG images on disk, attach or view the JavaScript
-source on them, and view/edit metadata.
-
-```bash
-# (the $ represents the shell prompt in a command-line terminal)
-
-# See metadata about a doodad file.
-$ doodad show /path/to/custom.doodad
-
-# Create a new doodad based on PNG images on disk.
-$ doodad convert frame0.png frame1.png frame2.png output.doodad
-
-# Add and view a custom script attached to the doodad.
-$ doodad install-script index.js custom.doodad
-$ doodad show --script custom.doodad
-```
-
-More info on the [`doodad` tool](../doodad-tool.md) here.
diff --git a/dev-assets/guidebook/docs/custom-doodads/scripts.md b/dev-assets/guidebook/docs/custom-doodads/scripts.md
deleted file mode 100644
index 7f9a2d8..0000000
--- a/dev-assets/guidebook/docs/custom-doodads/scripts.md
+++ /dev/null
@@ -1,564 +0,0 @@
-# Doodad Scripts
-
-Doodads are programmed using JavaScript which gives them their behavior
-and ability to interact with the player and other doodads.
-
-Doodad scripts are run during "Play Mode" when a level _containing_ the doodad
-is being played. You can install a JavaScript (.js) file into a doodad using
-the command-line `doodad` program.
-
-An example Doodad script looks like the following:
-
-```javascript
-// main() is called on level initialization for each
-// instance ("actor") of the doodad.
-function main() {
-    // Logs go to the game's log file (standard output on Linux/Mac).
-    console.log("%s initialized!", Self.Title);
-
-    // If our doodad has 'solid' parts that should prohibit movement,
-    // define the hitbox here. Coordinates are relative so 0,0 is the
-    // top-left pixel of the doodad's sprite.
-    Self.SetHitbox(0, 0, 64, 12);
-
-    // Handle a collision when another doodad (or player) has entered
-    // the space of our doodad.
-    Events.OnCollide(function(e) {
-        // The `e` object holds information about the event.
-        console.log("Actor %s has entered our hitbox!", e.Actor.ID());
-
-        // InHitbox is `true` if we defined a hitbox for ourselves, and
-        // the colliding actor is inside of the hitbox we defined.
-        if (e.InHitbox) {
-            // To prohibit movement, return false from the OnCollide handler.
-            // If you don't return false, the actor is allowed to keep on
-            // moving through.
-            return false;
-        }
-
-        // When movement is finalized, OnCollide is called one final time
-        // with e.Settled=true; it is only then that a doodad should run
-        // event handlers for a logical collide event.
-        if (e.Settled) {
-            // do something
-            Message.Publish("power", true);
-        }
-    });
-
-    // OnLeave is called when an actor, who was previously colliding with
-    // us, is no longer doing so.
-    Events.OnLeave(function(e) {
-        console.log("Actor %s has stopped colliding!", e.Actor.ID());
-    })
-}
-```
-
-# Installing a Doodad Script
-
-Use the command-line `doodad` tool to attach a script to your doodad file:
-
-```bash
-# Attach the JavaScript at "script.js" to the doodad file "filename.doodad"
-doodad install-script script.js filename.doodad
-
-# To view the script currently attached to a doodad
-# (prints the script to your terminal)
-doodad show --script filename.doodad
-```
-
-# Testing Your Script
-
-The best way to test your doodad script is to use it in a level!
-
-Run the game in a console to watch the log output, and you can use functions
-like `console.log()` in your script to help debug issues. Drag your custom
-doodad into a level and playtest it! Your script's main() function is called
-when the level instance of your doodad is initialized.
-
-# JavaScript API
-
-The following global variables are available to all Doodad scripts.
-
-## Self
-
-Self holds data about the current doodad instance loaded inside of a level.
-
-**String attributes:**
-
-* Self.Title: the doodad title.
-* Self.Filename: the doodad filename (useful for inventory items).
-
-Methods are below.
-
-### Self.ID() string
-
-Returns the "actor ID" of the doodad instance loaded inside of a level. This
-is usually a random UUID string that was saved with the level data.
-
-### Self.GetTag(string name) string
-
-Return a "tag" that was saved with the doodad's file data.
-
-Tags are an arbitrary key/value data store attached to the doodad file.
-You can use the `doodad.exe` tool shipped with the game to view and manage tags
-on your own custom doodads:
-
-```bash
-# Command-line doodad tool usage:
-
-# Show information about a doodad, look for the "Tags:" section.
-doodad show filename.doodad
-
-# Set a tag. "-t" for short.
-doodad edit-doodad --tag 'color=blue' filename.doodad
-
-# Set the tag to empty to remove it.
-doodad edit-doodad -t 'color=' filename.doodad
-```
-
-This is useful for a set of multiple doodads to share the same script but
-have different behavior depending on how each is tagged.
-
-### Self.Position() Point
-
-Returns the doodad's current position in the level.
-
-Point is an object with .X and .Y integer values.
-
-```javascript
-var p = Self.Position()
-console.log("I am at %d,%d", p.X, p.Y)
-```
-
-### Self.SetHitbox(x, y, w, h int)
-
-Configure the "solid hitbox" of this doodad.
-
-The X and Y coordinates are relative to the doodad's sprite: (0,0) is the top
-left pixel of the doodad. The W and H are the width and height of the hitbox
-starting at those coordinates.
-
-When another doodad enters the area of your doodad's sprite (for example, the
-player character has entered the square shape of your doodad sprite) your script
-begins to receive OnCollide events from the approaching actor.
-
-The OnCollide event tells you if the invading doodad is inside your custom
-hitbox which you define here (`InHitbox`) making it easy to make choices based
-on that status.
-
-Here's an example script for a hypothetical "locked door" doodad that acts
-solid but only on a thin rectangle in the middle of its sprite:
-
-```javascript
-// Example script for a "locked door"
-function main() {
-    // Suppose the doodad's sprite size is 64x64 pixels square.
-    // The door is in side profile where the door itself ranges from pixels
-    //    (20, 0) to (24, 64)
-    Self.SetHitbox(20, 0, 24, 64)
-
-    // OnCollide handlers.
-    Events.OnCollide(function(e) {
-        // The convenient e.InHitbox tells you if the colliding actor is
-        // inside the hitbox we defined.
-        if (e.InHitbox) {
-            // Return false to protest the collision (act solid).
-            return false;
-        }
-    });
-}
-```
-
-### Self.SetVelocity(Velocity)
-
-Set the doodad's velocity. Velocity is a type that can be created with the
-Velocity() constructor, which takes an X and Y value:
-
-```javascript
-Self.SetVelocity( Velocity(3.2, 7.0) );
-```
-
-A positive X velocity propels the doodad to the right. A positive Y velocity
-propels the doodad downward.
-
-### Self.SetMobile(bool)
-
-Call `SetMobile(true)` if the doodad will move on its own.
-
-This is for mobile doodads such as the player character and enemy mobs.
-Stationary doodads like buttons, doors, and trapdoors do not mark themselves
-as mobile.
-
-Mobile doodads incur extra work for the game doing collision checking so only
-set this to `true` if your doodad will move (i.e. changes its Velocity or
-Position).
-
-```javascript
-Self.SetMobile(true);
-```
-
-### Self.SetGravity(bool)
-
-Set whether gravity applies to this doodad. By default doodads are stationary
-and do not fall downwards. The player character and some mobile enemies that
-want to be affected by gravity should opt in to this.
-
-```javascript
-Self.SetGravity(true);
-```
-
-### Self.ShowLayer(index int)
-
-Switch the active layer of the doodad to the layer at this index.
-
-A doodad file can contain multiple layers, or images. The first and default
-layer is at index zero, the second layer at index 1, and so on.
-
-```javascript
-Self.ShowLayer(0);  // 0 is the first and default layer
-Self.ShowLayer(1);  // show the second layer instead
-```
-
-### Self.ShowLayerNamed(name string)
-
-Switch the active layer by name instead of index.
-
-Each layer has an arbitrary name that it can be addressed by instead of needing
-to keep track of the layer index.
-
-Doodads created by the command-line `doodad` tool will have their layers named
-automatically by their file name. The layer **indexes** will retain the same
-order of file names passed in, with 0 being the first file:
-
-```bash
-# Doodad tool-created doodads have layers named after their file names.
-# example "open-1.png" will be named "open-1"
-doodad convert door.png open-1.png open-2.png open-3.png my-door.doodad
-```
-
-### Self.AddAnimation(name string, interval int, layers list)
-
-Register a named animation for your doodad. `interval` is the time in
-milliseconds before going to the next frame. `layers` is an array of layer
-names or indexes to be used for the animation.
-
-Doodads can animate by having multiple frames (images) in the same file.
-Layers are ordered (layer 0 is the first, then increments from there) and
-each has a name. This function can take either identifier to specify
-which layers are part of the animation.
-
-```javascript
-// Animation named "open" using named layers, 100ms delay between frames.
-Self.AddAnimation("open", 100, ["open-1", "open-2", "open-3"]);
-
-// Animation named "close" using layers by index.
-Self.AddAnimation("close", 100, [3, 2, 1]);
-```
-
-### Self.PlayAnimation(name string, callback func())
-
-This starts playing the named animation. The callback function will be called
-when the animation has completed.
-
-```javascript
-Self.PlayAnimation("open", function() {
-    console.log("I've finished opening!");
-
-    // The callback is optional; use null if you don't need it.
-    Self.PlayAnimation("close", null);
-});
-```
-
-### Self.IsAnimating() bool
-
-Returns true if an animation is currently being played.
-
-### Self.StopAnimation()
-
-Stops any currently playing animation.
-
-
-* Self.Doodad(): a pointer to the doodad's file data.
-  * Self.Doodad().Title: get the title of the doodad file.
-  * Self.Doodad().Author: the name of the author who wrote the doodad.
-  * Self.Doodad().Script: the doodad's JavaScript source code. Note that
-    modifying this won't have any effect in-game, as the script had already
-    been loaded into the interpreter.
-  * Self.Doodad().GameVersion: the version of {{ app_name }} that was used
-    when the doodad was created.
-
-### Self.Destroy()
-
-This destroys the current instance of the doodad as it appears in a level.
-
-For example, a Key destroys itself when it's picked up so that it disappears
-from the level and can't be picked up again. Call this function when the
-doodad instance should be destroyed and removed from the active level.
-
------
-
-## Console Logging
-
-Like in node.js and the web browser, `console.log` and friends are available
-for logging from a doodad script. Logs are emitted to the same place as the
-game's logs are.
-
-```javascript
-console.log("Hello world!");
-console.log("Interpolate strings '%s' and numbers '%d'", "string", 123);
-console.debug("Debug messages shown when the game is in debug mode");
-console.warn("Warning-level messages");
-console.error("Error-level messages");
-```
-
------
-
-## Timers and Intervals
-
-Like in a web browser, functions such as setTimeout and setInterval are
-supported in doodad scripts.
-
-### setTimeout(function, milliseconds int) int
-
-setTimeout calls your function after the specified number of milliseconds.
-
-1000ms are in one second.
-
-Returns an integer "timeout ID" that you'll need if you want to cancel the
-timeout with clearTimeout.
-
-### setInterval(function, milliseconds int) int
-
-setInterval calls your function repeatedly after every specified number of
-milliseconds.
-
-Returns an integer "interval ID" that you'll need if you want to cancel the
-interval with clearInterval.
-
-### clearTimeout(id int)
-
-Cancels the timeout with the given ID.
-
-### clearInterval(id int)
-
-Cancels the interval with the given ID.
-
------
-
-## Type Constructors
-
-Some methods may need data of certain native types that aren't available in
-JavaScript. These global functions will initialize data of the correct types:
-
-### RGBA(red, green, blue, alpha uint8)
-
-Creates a Color type from red, green, blue and alpha values (integers between
-0 and 255).
-
-### Point(x, y int)
-
-Creates a Point object with X and Y coordinates.
-
-### Vector(x, y float64)
-
-Creates a Vector object with X and Y dimensions.
-
------
-
-## Global Functions
-
-Some useful globally available functions:
-
-### EndLevel()
-
-This ends the current level, i.e. to be used by the goal flag.
-
-### Flash(message string, args...)
-
-Flash a message on screen to the user.
-
-Flashed messages appear at the bottom of the screen and fade out after a few
-moments. If multiple messages are flashed at the same time, they stack from the
-bottom of the window with the newest message on bottom.
-
-Don't abuse this feature as spamming it may annoy the player.
-
-### GetTick() uint64
-
-Returns the current game tick. This value started at zero when the game was
-launched and increments every frame while running.
-
-### time.Now() time.Time
-
-This exposes the Go standard library function `time.Now()` that returns the
-current date and time as a Go time.Time value.
-
-### time.Add(t time.Time, milliseconds int64) time.Time
-
-Add a number of milliseconds to a Go Time value.
-
---------
-
-## Event Handlers
-
-Doodad scripts can respond to certain events using functions on the global
-`Events` variable.
-
-### Events.OnCollide( func(event) )
-
-OnCollide is called when another actor is colliding with your doodad's sprite
-box. The function is given a CollideEvent object which has the following
-attributes:
-
-* Actor: the doodad which is colliding with your doodad.
-* Overlap (Rect): a rectangle of where the two doodads' boxes are overlapping,
-  relative to your doodad sprite's box. That is, if the Actor was moving in from
-  the left side of your doodad, the X value would be zero and W would be the
-  number of pixels of overlap.
-* InHitbox (bool): true if the colliding actor's hitbox is intersecting with
-  the hitbox you defined with SetHitbox().
-* Settled (bool): This is `false` when the game is trying to move the colliding
-  doodad and is sussing out whether or not your doodad will act solid and
-  protest its movement. When the game has settled the location of the colliding
-  doodad it will call OnCollide a final time with Settled=true. If your doodad
-  has special behavior when touched (i.e. a button that presses in), you should
-  wait until Settled=true before running your handler for that.
-
-### Events.OnLeave( func(event) )
-
-Called when an actor that _was_ colliding with your doodad is no longer
-colliding (or has left your doodad's sprite box).
-
-### Events.RunKeypress( func(event) )
-
-Handle a keypress. `event` is an `event.State` from the render engine.
-
-TODO: document that.
-
------
-
-## Pub/Sub Communication
-
-Doodads in a level are able to send and receive messages to other doodads,
-either those that they are **linked** to or those that listen on a more
-'broadcast' frequency.
-
-> **Linking** is when the level author connected two doodads together with
-> the Link Tool. The two doodads' scripts can communicate with each other
-> in-game over that link.
-
-For example, if the level author links a Button to an Electric Door, the button
-can send a "power" event to the door so that it can open when a player touches
-the button.
-
-Doodads communicate in a "publisher/subscriber" model: one doodad publishes an
-event with a name and data, and other doodads subscribe to the named event to
-receive that data.
-
-### Official, Standard Pub/Sub Messages
-
-The following message names and data types are used by the game's default
-doodads. You're free to use these in your own custom doodads.
-
-If extending this list with your own custom events, be careful to choose a
-unique namespace to prevent collision with other users' custom doodads and
-their custom event names.
-
-| Name | Data Type | Description |
-|------|-----------|--------------|
-| power | boolean | Communicates a "powered" (true) or "not powered" state, as in a Button to an Electric Door. |
-| broadcast:state-change | boolean | An "ON/OFF" button was hit and all state blocks should flip. |
-
-### Message.Publish(name string, data...)
-
-Publish a named message to all of your **linked** doodads.
-
-`data` is a list of arbitrary arguments to send with the message.
-
-```javascript
-// Example button doodad that emits a "power" (bool) state to linked doodads
-// that subscribe to this event.
-function main() {
-    // When an actor collides with the button, emit a powered state.
-    Events.OnCollide(function(e) {
-        Message.Publish("power", true);
-    });
-
-    // When the actor leaves the button, turn off the power.
-    Events.OnLeave(function(e) {
-        Message.Publish("power", false);
-    })
-}
-```
-
-### Message.Subscribe(name string, function)
-
-Subscribe to a named message from any **linked** doodads.
-
-The function receives the data that was passed with the message. Its data type
-is arbitrary and will depend on the type of message.
-
-```javascript
-// Example electronic device doodad that responds to power from linked buttons.
-function main() {
-    // Boolean to store if our electric device has juice.
-    var powered = false;
-
-    // Do something while powered
-    setInterval(function() {
-        if (powered) {
-            console.log("Brmm...")
-        }
-    }, 1000);
-
-    // Subscribe to the `power` event by a linked button or other power source.
-    Message.Subscribe("power", function(boolValue) {
-        console.log("Powered %s!", boolValue === true ? "on" : "off");
-        powered = boolValue;
-    });
-}
-```
-
-### Message.Broadcast(name string, data...)
-
-This publishes a named message to **every** doodad in the level, whether it
-was linked to the broadcaster or not.
-
-For example the "ON/OFF" button globally toggles a boolean state in every
-state block that subscribes to the `broadcast:state-change` event.
-
-If you were to broadcast an event like `power` it would activate every single
-power-sensitive doodad on the level.
-
-```javascript
-// Example two-state block that globally receives the state-change broadcast.
-function main() {
-    var myState = false;
-    Message.Subscribe("broadcast:state-change", function(boolValue) {
-      // Most two-state blocks just flip their own state, ignoring the
-      // boolValue passed with this message.
-      myState = !myState;
-    });
-}
-
-// Example ON/OFF block that emits the state-change broadcast. It also
-// subscribes to the event to keep its own state in sync with all the other
-// ON/OFF blocks on the level when they get hit.
-function main() {
-    var myState = false;
-
-    // Listen for other ON/OFF button activations to keep our state in
-    // sync with theirs.
-    Message.Subscribe("broadcast:state-change", function(boolValue) {
-        myState = boolValue;
-    });
-
-    // When collided with, broadcast the state toggle to all state blocks.
-    Events.OnCollide(function(e) {
-        if (e.Settled) {
-            myState = !!myState;
-            Message.Broadcast("broadcast:state-change", myState);
-        }
-    })
-}
-```
diff --git a/dev-assets/guidebook/docs/custom-levels/index.md b/dev-assets/guidebook/docs/custom-levels/index.md
deleted file mode 100644
index cd9369e..0000000
--- a/dev-assets/guidebook/docs/custom-levels/index.md
+++ /dev/null
@@ -1,99 +0,0 @@
-# Creating Custom Levels
-
-One of the core gameplay features is its Level Editor which lets you draw your
-own custom maps to play and share with others.
-
-From the game's Main Menu, click on the "Create a Level" button to open the
-level editor. To edit an existing custom level, click on the "Edit a Level"
-button instead.
-
-## Level Properties
-
-When creating a new level, you first choose some settings for it. These are
-described below:
-
-### Page Type
-
-This setting controls the size and boundaries of your level, and control the
-appearance of the notebook paper background of your level.
-
-* **Bounded** is the default. The camera won't scroll past the top-left corner
-  of the page (0,0), and the level size is capped to 2550x3300, or the
-  approximate size of an 11:9 standard sheet of notebook paper in pixels.
-* **No Negative Space** is like Bounded, but the width and height of the level
-  have no boundary. Levels can grow "infinitely" to the right and downward
-  but no negative coordinates past the top or left edge.
-* **Unbounded** allows for "infinite" sized maps that give unlimited room to
-  grow your level. The wallpaper on this level type only uses the "tiling"
-  pattern, so notebook-themed levels won't show the top/left decorations.
-
-### Wallpaper
-
-The wallpaper affects the "theme" of your level. Project: Doodle is themed around
-hand-drawn mazes on paper, so the built-in themes look like various kinds of
-paper.
-
-* **Notebook** looks like standard ruled notebook paper. It's a white paper with
-  blue horizontal lines, a single red vertical line down the left, and a wide
-  margin on the top and left edges.
-* **Legal Pad** looks like ruled yellow legal pad. It's similar to Notebook but
-  has yellow paper and a second vertical red line down the left.
-* **Blueprint** is a dark blueprint paper background with a repeating grid pattern.
-  Notably, the default Color Palette for this theme is different than normal:
-  "solid" lines are white instead of black, to show up better against the dark
-  background.
-
-The decorations of the wallpaper vary based on the Page Type. For example, the
-Notebook and Legal Pad have extra padding on the top of the page and red lines
-going down just the left side, and the rest of the level uses the repeating blue
-lines pattern. The page types and their effect on the wallpapers are:
-
-* **Bounded** and **No Negative Space** will show the decorations for the top
-  and left edges of the page, as these levels are bounded on their top/left
-  corner.
-* **Unbounded** levels only use the repeating tiled pattern across the entire
-  level, because there is no top-left boundary to anchor those decorations to.
-
-## Editor Mode Interface
-
-![Level Editor View](../images/editor-1.png)
-
-Quick 5-minute tour of what you're looking at:
-
-* The top of the window has your **Menu Bar**:
-    * **New Level** opens the "Create a New Level" menu.
-    * **New Doodad** opens the Doodad Editor for drawing a new custom doodad.
-      You're prompted for the size of the doodad, which will be its width and
-      height boundary. For example, a size of "100" means a 100x100 pixel graphic
-      for your custom doodad.
-    * **Save** and **Save as...** let you save the current Level or Doodad you're
-      drawing to disk. "Save" will only ask for the filename once whereas "Save as"
-      asks every time.
-    * **Load** opens the "Edit a Level" menu to choose a Level or Doodad to edit.
-    * **Options** options the Level Options dialog so you can modify the page type
-      and wallpaper setting.
-* The panel on the left side of the window is your **Tool Box**. Clicking these
-  buttons activates a specific drawing tool or mode:
-    * **Pencil Tool** lets you click, drag, and draw pixels of your selected
-      Palette color onto your level freehand.
-    * **Line Tool** lets you easily draw a straight line between two points. Click
-      in your level where you want the first point to be, and drag your mouse to
-      the second point. Release the mouse to commit the line to your drawing.
-    * **Rectangle Tool** lets you easily draw rectangles on your level.
-    * **Ellipse Tool** lets you draw circles or elliptical shapes.
-    * **Doodad Tool** lets you drag doodads such as buttons and doors onto your
-      level. See the [Doodad Tool](#doodad-tool) below.
-    * **Link Tool** lets you link doodads together so that they can interact off
-      each other. For example, a Button connected to an Electric Door will cause
-      the door to open and close when the button is pressed. See [Link Tool](#link-tool)
-      below.
-    * **Eraser Tool** cleans up your mistakes. Click and drag over pixels you've
-      drawn to delete the pixels from your level.
-    * **Brush Size:** the "Size:" label shows the brush size of your current drawing
-      tool. This translates to the line thickness, or how big your pixels are when
-      drawn into the level. Click the + and - buttons to increase or decrease the
-      brush size, and draw thicker or thinner lines.
-* The panel on the right side of the window is your **Palette** of colors to
-  draw with.
-
-![Doodad Toolbar View](../images/editor-2.png)
diff --git a/dev-assets/guidebook/docs/doodad-tool.md b/dev-assets/guidebook/docs/doodad-tool.md
deleted file mode 100644
index 02c3ef0..0000000
--- a/dev-assets/guidebook/docs/doodad-tool.md
+++ /dev/null
@@ -1,118 +0,0 @@
-# Doodad Tool
-
-The game ships with a command-line program called `doodad` which assists in
-creating and managing custom doodads and levels.
-
-The `doodad` tool can show and set details on .doodad and .level files used by
-the game, create new doodads from PNG images and attach custom JavaScript source
-to program behavior of doodads.
-
-## Where to Find It
-
-The `doodad` tool should be in the same place as the game executable.
-
-On Windows, the program is called `doodad.exe` and comes in the zip file next
-to the game executable, `doodle.exe`.
-
-On Linux, it will typically be at `/opt/project-doodle/doodad`.
-
-On Mac OS, it is found inside the .app bundle.
-
-## Usage
-
-Run `doodad --help` to get usage information.
-
-The program includes several sub-commands, such as `doodad convert`. Type a
-subcommand and `--help` to get help on that command, for example:
-
-```bash
-doodad convert --help
-```
-
-# Examples
-
-Here are some common scenarios and use cases for the doodad tool.
-
-## Show
-
-```bash
-# Usage:
-doodad show [doodad or level filename]
-```
-
-Shows metadata and details about a level or doodad file.
-
-Examples:
-
-```bash
-$ doodad show button.doodad
-===== Doodad: button.doodad =====
-Headers:
-  File version: 1
-  Game version: 0.0.10-alpha
-  Doodad title: Button
-        Author: Noah
-        Locked: true
-        Hidden: false
-   Script size: 473 bytes
-
-Palette:
-  - Swatch name: Color<#000000+ff>
-    Attributes:  solid
-    Color:       #000000
-  - Swatch name: Color<#666666+ff>
-    Attributes:  none
-    Color:       #666666
-  - Swatch name: Color<#999999+ff>
-    Attributes:  fire
-    Color:       #999999
-
-Layer 0: button1
-Chunks:
-  Pixels Per Chunk: 37^2
-  Number Generated: 1
-  Coordinate Range: (0,0) ... (36,36)
-  World Dimensions: 36x36
-  Use -chunks or -verbose to serialize Chunks
-
-Layer 1: button2
-Chunks:
-  Pixels Per Chunk: 37^2
-  Number Generated: 1
-  Coordinate Range: (0,0) ... (36,36)
-  World Dimensions: 36x36
-  Use -chunks or -verbose to serialize Chunks
-```
-
-## Convert
-
-```bash
-# Usage:
-doodad convert [options] <input files.png> <output file.doodad>
-```
-
-### Creating a Doodad from PNG images
-
-Suppose you have PNG images named "frame0.png" through "frame3.png" and want
-to create a doodad from those images. This will convert them to the doodad
-file "custom.doodad":
-
-```bash
-# Convert PNG images into a doodad.
-doodad convert frame0.png frame1.png frame2.png frame3.png custom.doodad
-
-# The same, but also attach custom tags with the doodad.
-doodad convert --tag color=blue frame{0,1,2,3}.png custom.doodad
-```
-
-### Convert a level to a PNG image
-
-```bash
-doodad convert my.level output.png
-```
-
-### Create a level from a PNG image
-
-```bash
-doodad convert level.png output.level
-```
diff --git a/dev-assets/guidebook/docs/images/editor-1.png b/dev-assets/guidebook/docs/images/editor-1.png
deleted file mode 100644
index ff354b8..0000000
Binary files a/dev-assets/guidebook/docs/images/editor-1.png and /dev/null differ
diff --git a/dev-assets/guidebook/docs/images/editor-2.png b/dev-assets/guidebook/docs/images/editor-2.png
deleted file mode 100644
index 1c48074..0000000
Binary files a/dev-assets/guidebook/docs/images/editor-2.png and /dev/null differ
diff --git a/dev-assets/guidebook/docs/images/main-menu.png b/dev-assets/guidebook/docs/images/main-menu.png
deleted file mode 100644
index ddd7db1..0000000
Binary files a/dev-assets/guidebook/docs/images/main-menu.png and /dev/null differ
diff --git a/dev-assets/guidebook/docs/index.md b/dev-assets/guidebook/docs/index.md
deleted file mode 100644
index a09f86a..0000000
--- a/dev-assets/guidebook/docs/index.md
+++ /dev/null
@@ -1,15 +0,0 @@
-# Welcome to Project: Doodle
-
-![](images/main-menu.png)
-
-[Project: Doodle](about.md) is a drawing-based maze game themed around hand-drawn
-maps on paper. You can draw a level for a 2D platformer game, drag-and-drop
-"doodads" such as buttons and doors into your level, and play it.
-
-## Table of Contents
-
-* [Creating Custom Levels](custom-levels/)
-* [Creating Custom Doodads](custom-doodads/)
-    * [Draw Sprites In-Game](custom-doodads/edit-in-game.md)
-    * [Draw Sprites with an External Program](custom-doodads/edit-external.md)
-    * [Program Them with JavaScript](custom-doodads/scripts.md)
diff --git a/dev-assets/guidebook/mkdocs.yml b/dev-assets/guidebook/mkdocs.yml
deleted file mode 100644
index b6b75f3..0000000
--- a/dev-assets/guidebook/mkdocs.yml
+++ /dev/null
@@ -1,8 +0,0 @@
-site_name: "Project: Doodle Guidebook"
-nav:
-  - Home: index.md
-  - About: about.md
-  - "Custom Doodads": custom-doodads/index.md
-markdown_extensions:
-  - toc:
-      permalink: "#"
diff --git a/dev-assets/guidebook/requirements.txt b/dev-assets/guidebook/requirements.txt
deleted file mode 100644
index f27036f..0000000
--- a/dev-assets/guidebook/requirements.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-markdown
-jinja2
diff --git a/go.mod b/go.mod
index 96cf3ab..f2b845d 100644
--- a/go.mod
+++ b/go.mod
@@ -11,12 +11,18 @@ require (
 	git.kirsle.net/go/render v0.0.0-20200710023247-e5f4c3a16860
 	git.kirsle.net/go/ui v0.0.0-20200710023146-e2a561fbd04c
 	github.com/alecthomas/gocyclo v0.0.0-20150208221726-aa8f8b160214 // indirect
+	github.com/alexkohler/nakedret v1.0.0 // indirect
+	github.com/client9/misspell v0.3.4 // indirect
 	github.com/google/uuid v1.1.2
 	github.com/gordonklaus/ineffassign v0.0.0-20201107091007-3b93a8888063 // indirect
 	github.com/jgautheron/goconst v0.0.0-20201108215931-f8e4fe8351cd // indirect
 	github.com/kirsle/configdir v0.0.0-20170128060238-e45d2f54772f
+	github.com/kisielk/errcheck v1.4.0 // indirect
 	github.com/mdempsky/maligned v0.0.0-20201101000000-d73c43cb16d0 // indirect
+	github.com/mdempsky/unconvert v0.0.0-20200228143138-95ecdbfc0b5f // indirect
+	github.com/opennota/check v0.0.0-20180911053232-0c771f5545ff // indirect
 	github.com/robertkrimen/otto v0.0.0-20200922221731-ef014fd054ac
+	github.com/stripe/safesql v0.2.0 // indirect
 	github.com/tomnomnom/xtermcolor v0.0.0-20160428124646-b78803f00a7e // indirect
 	github.com/urfave/cli v1.22.5
 	github.com/urfave/cli/v2 v2.3.0
@@ -27,6 +33,7 @@ require (
 	golang.org/x/image v0.0.0-20200927104501-e162460cd6b5
 	google.golang.org/appengine v1.6.7 // indirect
 	gopkg.in/sourcemap.v1 v1.0.5 // indirect
+	honnef.co/go/tools v0.0.1-2020.1.6 // indirect
 	mvdan.cc/interfacer v0.0.0-20180901003855-c20040233aed // indirect
 	mvdan.cc/lint v0.0.0-20170908181259-adc824a0674b // indirect
 	mvdan.cc/unparam v0.0.0-20200501210554-b37ab49443f7 // indirect
diff --git a/go.sum b/go.sum
index 636d3c9..1a7e73a 100644
--- a/go.sum
+++ b/go.sum
@@ -13,15 +13,21 @@ git.kirsle.net/go/render v0.0.0-20200710023247-e5f4c3a16860 h1:0jaJRNlBb/OCB/QSk
 git.kirsle.net/go/render v0.0.0-20200710023247-e5f4c3a16860/go.mod h1:ss7pvZbGWrMaDuZwyUTjV9+T0AJwAkxZZHwMFsvHrkk=
 git.kirsle.net/go/ui v0.0.0-20200710023146-e2a561fbd04c h1:8fvCXsFGK91WtiTIAdklAN3gHVNYD0hvFvWfznCLMGc=
 git.kirsle.net/go/ui v0.0.0-20200710023146-e2a561fbd04c/go.mod h1:Q93RpHNXvbGr3dQ9mmcEN8ZC3dtNQ4FwivSx53tKOVA=
+github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/alecthomas/gocyclo v0.0.0-20150208221726-aa8f8b160214 h1:YI/8G3uLbYyowJeOPVL6BMKe2wbL54h0FdEKmncU6lU=
 github.com/alecthomas/gocyclo v0.0.0-20150208221726-aa8f8b160214/go.mod h1:Ef5UOtJdJ5rVFObdOVsrNgKV/Wf4I+daTCSk8GTrHIk=
 github.com/alexflint/go-arg v0.0.0-20160306200701-e71d6514f40a h1:Bc+P30eTWphhueyACA/fjiHJXRDq/kGiqO38nGxvml0=
 github.com/alexflint/go-arg v0.0.0-20160306200701-e71d6514f40a/go.mod h1:PHxo6ZWOLVMZZgWSAqBynb/KhIqoGO6WKwOVX7rM9dg=
+github.com/alexkohler/nakedret v1.0.0 h1:S/bzOFhZHYUJp6qPmdXdFHS5nlWGFmLmoc8QOydvotE=
+github.com/alexkohler/nakedret v1.0.0/go.mod h1:tfDQbtPt67HhBK/6P0yNktIX7peCxfOp0jO9007DrLE=
+github.com/client9/misspell v0.3.4 h1:ta993UF76GwbvJcIo3Y68y/M3WxlpEHPWIGDkJYwzJI=
+github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d h1:U+s90UTSYgptZMwQh2aRr3LuazLJIa+Pg3Kc1ylSYVY=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/golang/protobuf v1.3.1 h1:YF8+flBXS5eO826T4nzqPrxfhQThhXl0YzfuUPu4SBg=
 github.com/golang/protobuf v1.3.1/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
 github.com/google/uuid v1.1.2 h1:EVhdT+1Kseyi1/pUmXKaFxYsDNy9RQYkMWRH68J/W7Y=
 github.com/google/uuid v1.1.2/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/gordonklaus/ineffassign v0.0.0-20201107091007-3b93a8888063 h1:dKprcOvlsvqfWn/iGvz+oYuC2axESeSMuF8dDrWMNsE=
@@ -30,6 +36,8 @@ github.com/jgautheron/goconst v0.0.0-20201108215931-f8e4fe8351cd h1:xfrCuNSOStub
 github.com/jgautheron/goconst v0.0.0-20201108215931-f8e4fe8351cd/go.mod h1:aAosetZ5zaeC/2EfMeRswtxUFBpe2Hr7HzkgX4fanO4=
 github.com/kirsle/configdir v0.0.0-20170128060238-e45d2f54772f h1:dKccXx7xA56UNqOcFIbuqFjAWPVtP688j5QMgmo6OHU=
 github.com/kirsle/configdir v0.0.0-20170128060238-e45d2f54772f/go.mod h1:4rEELDSfUAlBSyUjPG0JnaNGjf13JySHFeRdD/3dLP0=
+github.com/kisielk/errcheck v1.4.0 h1:ueN6QYA+c7eDQo7ebpNdYR8mUJZThiGz9PEoJEMGPzA=
+github.com/kisielk/errcheck v1.4.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0 h1:AV2c/EiW3KqPNT9ZKl07ehoAGi4C5/01Cfbblndcapg=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
@@ -37,14 +45,21 @@ github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/mdempsky/maligned v0.0.0-20201101000000-d73c43cb16d0 h1:+6XJvFZBYbNv/nSekNWFZyaGNMXcPnZ4n/HHoCXn+Ms=
 github.com/mdempsky/maligned v0.0.0-20201101000000-d73c43cb16d0/go.mod h1:3UB4iTzhLciyWcrrvXSkrtCIU+IJ5GCfEmnleHRsxL4=
+github.com/mdempsky/unconvert v0.0.0-20200228143138-95ecdbfc0b5f h1:Kc3s6QFyh9DLgInXpWKuG+8I7R7lXbnP7mcoOVIt6KY=
+github.com/mdempsky/unconvert v0.0.0-20200228143138-95ecdbfc0b5f/go.mod h1:AmCV4WB3cDMZqgPk+OUQKumliiQS4ZYsBt3AXekyuAU=
+github.com/opennota/check v0.0.0-20180911053232-0c771f5545ff h1:lRHufowVGvUvxGsPveAZOpSa/9T5Gpxg6d7UbHCA9MQ=
+github.com/opennota/check v0.0.0-20180911053232-0c771f5545ff/go.mod h1:tydB+MZxWpY8M/NRu7jQhND/mXuLAPsKcSV6JkzofsA=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
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+github.com/stripe/safesql v0.2.0 h1:xiefmCDd8c35PVSGrL2FhBiaKxviXnGziBDOpOejeBE=
+github.com/stripe/safesql v0.2.0/go.mod h1:q7b2n0JmzM1mVGfcYpanfVb2j23cXZeWFxcILPn3JV4=
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@@ -68,6 +83,7 @@ golang.org/x/crypto v0.0.0-20201112155050-0c6587e931a9/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/image v0.0.0-20200119044424-58c23975cae1/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/image v0.0.0-20200927104501-e162460cd6b5 h1:QelT11PB4FXiDEXucrfNckHoFxwt8USGY1ajP1ZF5lM=
 golang.org/x/image v0.0.0-20200927104501-e162460cd6b5/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
+golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
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@@ -91,11 +107,15 @@ golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f h1:+Nyd8tzPX9R7BWHguqsrbFdRx
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@@ -115,6 +135,8 @@ gopkg.in/sourcemap.v1 v1.0.5 h1:inv58fC9f9J3TK2Y2R1NPntXEn3/wjWHkonhIUODNTI=
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+honnef.co/go/tools v0.0.1-2020.1.6 h1:W18jzjh8mfPez+AwGLxmOImucz/IFjpNlrKVnaj2YVc=
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