Since I like the shadows and there isn't much else, I'll nitpick:
-Screen shake is unnecessary and would get me annoyed very quickly on a longer version of the game. Also, the pistol gives the same amount of it as the other weapons, but not grenade launcher explosion, which I would expect the only one to shake my screen due to an explosion, which tends to be stronger than a bullet shot.
-The shadow implementation is imperfect - it's possible for a line of pixels to appear on the lit side of a wall
-H is in a very uncomfortable position, holding WASD and the mouse when you die
-Shadows hide other objects but not walls - be more consistent - both or neither
-Things shoot at you from outside of the screen. Worst one.
Make this game into a larger Amorphous+ and it's gold.