2x0ng is a procedural puzzle-combat roguelike game rendered in an 8-bit retro style. Pronounce it "TOO-zong". You control a little pixel-person running through a procedurally-generated maze; with your bouncing, color-changing Squareball, you can match colors to unlock new areas, and destroy an onslaught of enemies as you make your way to the exit. The rest of the rules are for you to discover in-game.
I know the person who made this so you might think I'm just giving it 10 because I know him or something but that's not true. I'm giving it 10 because it's free and because the work that went into making it is incredible if you know all the details.