I wrote a 5 page document on a fighting game that my friend and I came up with about 7 years ago after a very long day of Vf3, SF3, and SFZ2. It was ridiculously complex, and of course that would be its downfall, but I'd sure as hell play it.
I have no damn idea where it is these days, but here's the jist of it (and this is all from memory, so possibly not quite right):
1) Buttons for each appendage (head, right/left arm, right/left leg.) Head button+appendage was supposed to guard with that individual appendage. Stamina gauge would help determine how quickly you could recover from an attack/how long you could combo out for.
2) Individual limb damage, so limbs could be broken and basically become useless. We wanted it to have a true impact on the game, requiring strategies to target opponent's weak spots. Full damage to the head resulted in a KO iirc. Guarding caused damage to the limb doing said guarding, so it was do your advantage to mix up how you protected yourself. Characters would have viable strategies to target specific limbs with strikes/joint locks to disable the opponent.
3) Bleeding could occur due to an attack or being scraped with broken glass (or something like being thrown through a window or pierced with a shiv), and would sap the stamina gauge slowly but surely. When it emptied it would work on that limb's damage meter.
4) Environmental interaction with walls/items/weapons (BROKEN GLASS FOOLS)
5) Countering could theoretically go on forever if both players had the skill, (and it wouldn't be easy to do so.) We never really got into exactly how to implement it. Throws were reversible in nearly every case, and could go on for a long while Giant Gram style if both players could do it.