Another mini-update...

I've changed the boss spawn rate from 1 each 100 blocks, to 1 each 50.

Added Alt+Enter to switch from windowed screen to fullscreen. Esc key now quits the game.

Added a "scanlines-like" filter that works on windowed mode and in some fullscreen resolutions (720p, 1080p...)

Added some color guides on the lower corners of the screen so you can see what is the previous (left corner) and next (right corner) color change. Very helpful in bosses.