Breaker
My entry for Ludum Dare 31, my second Ludum Dare. I originally described this one as "a mix between Tetris and Minecraft". Blocks fall from the sky, and the goal is just to punch them. If a block lands on you while you're not either dodging or jumping, you are crushed and it's game over. Some blocks shoot projectiles, some explode, and some contain a powerup that can help you clear large stacks of blocks. Eventually, a black hole appears, stirring the madness.
There are several different types of blocks. A red block that does nothing, a blue one that shoots bullets (which do damage other blocks), a metal block that takes a ton of hits to break, a bomb block that explodes 3 seconds after taking damage, and a chest block that reveals a powerup upon breaking.
This one turned out rather fun, I think. It got rated #90 in the "fun" category for LD31.