An idea, HellMOO as a forum game. Taking out all of the NSFW and forum rule breaking content and keeping the atmosphere and silliness in it. (Like bisecting crackheads with a fork).
Every player would have a way of getting back into the game but not the cost wouldn't be free of course. Regular ol' Joe could be cloned and have a sickness and loss of ability after being cloned, but he'll be alive and back into the game. A zombie could reanimate, get the negatives of reanimated like being sick or something, he would have his likely badass zombie abilities, reanimation, and all that jazz but there could be a bunch of negatives for it. There could also be other game changing knick knacks not in traditional HellMOO, like becoming your generic grey alien (And being friends with other generic aliens aswell), and stuff like becoming half bird and such.
There'd be obviously be a bunch of mutations that wouldn't be necessarily be always in a set location. But you'd get some interesting mutations in a nuclear plant. A lot more handwaved superpowers and such, and even if two guys get the same mutation it wouldn't be exactly the same thing. Certain people would shoot other people with certain mutations (Unless they somehow conceal it or something). I'd imagine there wouldn't be exact stats and attributes but instead of numbers there would be short descriptions of your ability at some value with maybe if numbers are used only the GM would know them.
I'd imagine the game would be for around 4-8 at it's minimum and maximum. Though I have all of the following, I doubt my ability at GMing something like this.