When I considered the health system for Ultima Ratio Regum, I realised I wanted to move away from having an HP-based system, wherein you have full control of your character at '1' and suddenly die upon reaching '0'. Originally, I was going to have a basic limb system - arms, legs, torso, head. Each limb would have health, but it wouldn't be visible on screen, and would go through a variety of injuries.
However, this was also too simple. Now, each creature - the player included - effectively has an 'inventory' full of all its limbs, allowing me to field as many heads, arms, legs, wings or tails on a creature as I could ever want. The game then figures out how the creature should function (e.g. how many legs can it lose and still walk?) and the creature is modeled appropriately! When a creature attacks another, it picks a limb to attack, just as the player can by scrolling up and down through the menu:
Each limb also consists of multiple parts. A head - assuming it is made from flesh - consists of the head itself, a skull, a jaw, a windpipe, a jugular, zero-to-many eyes, zero-to-many horns, and two ears. The jaw can be torn off; eyes taken out; and all manner of probably PG-13 certificate digitized violence awaits!
I'm now working on allowing weapons to become lodged in creatures. They will soon have the ability to be pushed; twisted; broken off; and other exciting ASCII brutality! You can read more on my devblog, Facebook page, or Twitter feed. The devblog is updated weekly on Mondays, and the Twitter/FB at least daily.