[Ide]

Still the standard I think.

One thing you should ask yourself when doing something away from the 'standard' is whether what you're doing is really a good idea or just being different to be different. Hit points is a good example. The problem with using a system based on limb condition and usability is that while it's more realistic it's not a great idea for a game where 75% of your time is taken up in combat. A new player could easily get both wrists broken, their eye gouged out, and their toes chopped off after just a few fights. Then what? Do you just add spells or healers, or some racial or class ability, to shine them up good as new? It's certainly a possibility, but it should make sense for your game.

If what you want is for combat to have more interesting tactical choices, and make players think twice about the long-term effects, perhaps there are other ways to accomplish that.

Anyway, I'm all for doing something different, but where I would focus is on the theme/setting rather than specific mechanics.

edit: I should say that the focus on theme/setting should include other mechanics not normally seen in a game. But I think you get more bang for your buck by looking at the mud as a whole and styling that rather than tweaking magic, combat, class tiers, etcetera.