Just a few minor things that aren't noted in-game that some people will find important:

-Escape pauses the game.

-The BetterPixels font is public domain and can be found here: http://www.pentacom.jp/pentacom/bitfontmaker2/gallery/?id=102

-Control + B activates a "bright" mode. Helps with players who have a harder time seeing darker colors, etc.

-Control + N runs the game at half speed (press again to disable). Useful for people with imperfect reflexes. This can also be done while the game is paused. Since this was added rather late in development, it doesn't always necessarily revert back to full framerate the moment you switch to a scene which isn't programmed to detect it. Use with care.

-Control + M disables music.

-Control + L activates a "removed screen shake" mode, which disables screen shaking.

-Control + I gives you 50 extra HP at any time.

-The boomerang can retrieve health pickups from a distance. Just thought you'd wanna know.