Donjon Krawl!

I’m as suspicious of free RPGs as you are, but I’m pretty sure this rules. A quote: “if you’re a hard-core dungeon crawling machine, you’ve probably not seen mechanics that allow players to drive the situation like these. If you’re some sort of narrativist bleeding-edge pansy that’s used to have players run everything, you’ve probably not had the chance to wallow in the blood of your enemies like this.”