final readme tweak

README.md

@@ -13,6 +13,28 @@ The latest build of the game is under Releases.
 [Send any feedback you wish](https://theindustriousrabbit.com/about) -- it's
 appreciated! -- but I really don't know when I'll get back to working on this.
 
+Use WASD to move, left mouse to fire, aim using your mouse. Shooting enemies
+restores health and gives you coins. If you earn enough coins, you can upgrade:
+
+* `P` will increase damage per shot
+* `O` permanently upgrades your max health and restores all your health
+* `I` will increase the amount of health you can get from shooting enemies
+
+There are two weapon pickups:
+
+* Yellow is a shotgun, firing a spread of three shots
+* Red doubles up your shots, potentially making it through more enemies
+
+Much of it is not working:
+
+* The game just starts.
+* The game doesn't end when you run out of health. Hit [Escape] to end the game.
+* The difficulty needs serious tuning.
+* It does not look good.
+* If you play for too long the game will likely crash.
+
+Try it out!
+
 ## Setup
 
 Builds are done on a host Linux system with Open Watcom 2.0 installed to