diff --git a/README.md b/README.md
index d979894..a8eb9fd 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,35 @@
 # Doodle
 
+Doodle is a drawing-based maze game written in Go.
+
+# Features
+
+(Eventually), the high-level, user-facing features for the game are:
+
+* **Draw your own levels** freehand and then play them like a 2D platformer
+  game.
+* In **Adventure Mode** you can play through a series of official example
+  levels that ship with the game.
+* In **Edit Mode** you can draw a map freehand-style and lay down physical
+  geometry, and mark which lines are solid or which ones behave like fire.
+* Drag and drop **Doodads** like buttons, doors and keys into your level and
+  link them together so that buttons open doors and levers activate devices.
+* In **Play Mode** you can play your level as a 2D platformer game where you
+  collect keys, watch out for enemies, and solve puzzles to get to the exit.
+* Easily **Share** your custom maps with friends.
+
+## Mod-friendly
+
+* Users can create **Custom Doodads** to extend the game with a scripting
+  language like JavaScript. The sprites and animations are edited in-game
+  in Edit Mode, but the scripting is done in your text editor.
+* In **Edit Mode** you can drag custom doodads into your maps.
+* To **Share** your maps, you can choose to **bundle** the custom
+  doodads inside your map file itself, so that other players can play
+  the map without needing to install the doodads separately.
+* If you receive a map with custom doodads, you can **install** the doodads
+  into your copy of the game and use them in your own maps.
+
 # Milestones
 
 As a rough idea of the milestones needed for this game to work:
@@ -17,15 +47,23 @@ As a rough idea of the milestones needed for this game to work:
   * The PNG I draw looks slightly different to what you see on the SDL canvas;
     maybe difference between `Renderer.DrawLine()` and my own algorithm or
     the anti-aliasing.
-* [ ] Create a custom map file format (protobufs maybe) and "screenshot" the
+* [x] Create a custom map file format (protobufs maybe) and "screenshot" the
   canvas into this custom file format.
-* [ ] Make the program able to read this file format and reproduce the same
+* [x] Make the program able to read this file format and reproduce the same
   pixels on the canvas.
 
 ## Platformer
 
-* [ ] Start implementing a platformer that uses the custom map format for its
-  rendering and collision detection.
+* [ ] Inflate the pixel history from the map file into a full lookup grid
+  of `(X,Y)` coordinates. This will be useful for collision detection.
+* [ ] Create a dummy player character sprite, probably just a
+  `render.Circle()`. In **Play Mode** run collision checks and gravity on
+  the player sprite.
+* [ ] Get basic movement and collision working. With a cleanup this can
+  make a workable **ALPHA RELEASE**
+* [ ] Wrap a Qt GUI around the SDL window to make the Edit Mode easier to
+  work with, with toolbars to select brushes and doodads and junk.
+* [ ] Work on support for solid vs. transparent, fire, etc. geometry.
 * [ ] ???
 
 # Building