Go down in the dungeon. Kill everything you meet. Backstab your friends and steal their stuff. Grab the treasure and run.
Admit it. You love it.
Munchkin captures the dungeon experience... with none of that stupid role-playing stuff. All you have to do is kill monsters and grab magic items. Don the Horny Helmet and the Boots of Butt-Kicking. Wield the Staff of Napalm... or maybe the Chainsaw of Bloody Dismemberment. Start by slaughtering the Potted Plant and the Drooling Slime and work your way up to the Plutonium Dragon!
This will be an adaptation of Steve Jackson Games' card game Munchkin to play-by-post.