My idea is a fairly simple one, really.
Undeads get inate bonuses to damage reduction (piercing, slashing, death magic, cold magic), some vulnerabilities (fire and blunt weapons), immunities to sleep, stun, mind control (basically anything that affects the mind), poison, bleeding, the obvious stuff. They get a substantial bonus to HPs.
On the other side, they can't heal unless they level up. They might stumble upon a powerful artefact now and then, or get a very rare opportunity to suck the life out of something, find a fountain of undeath, I'm just shooting vague concepts. The idea behind that would be punctual and rare findings that might restore some health for the savvy explorer.
The real trick about keeping the Undead alive would reside in the player's ability to manage a big health pool that just keeps going down. That would be tactical choices on the battlefield, knowing when to protect the character or have her fall back, adopt defensive strategies to spare some valuable health, as well as outside combat, knowing when to pick a fight, chosing to avoid conflict. Will you take side with your allies knowing that might be that one too many fight for the day? Will you sell one of your group members out if it meant saving some of your precious decaying health? Or Would you be the martyr up front, trusting, hoping that your team mates will have your back?
Making decisions. Is this fight really worth it? Can I afford it? I think it goes well with the global idea of competitive cooperation that they are trying to push forward. Might also make players think about why, sometimes, they'll want to take the darker approach. It is, after all, the Undead.
Ah, okay, thanks for the clarification. I just wanted to know what you meant before I posted my response. So this is in part a response to your previous post:
Well one problem with looking at the upkeep of a living character in a videogame for a starting point is that there ISN'T any. Which is because as you pointed out - upkeep is annoying.
I'm not so sure about making it a struggle to keep an undead character going until the next level-up. The first reason is because each combat encounter is intended to be challenging enough to be dangerous. If all those buffs to an undead's surviability make them so much tankier than normal characters, that'll let undead steamroll encounters intended to be challenging.
The second reason is that if the buffs don't make the undead able to survive easily, then the undead will be worn down by attrition. Level-ups are definitely not frequent, and they get even less so the farther you go (which is also the time when enemies get more dangerous). Having only very rare chances to heal will kill a lot of characters by attrition and small mistakes, especially gamers who are less experienced.
I believe that Undead characters are supposed to be equally viable choices as a race, not just some kind of punishing hard mode, So I think healing as an undead should be more forgiving than your proposal.
(I also think that making them immune to sleep, stun, and mind-control on top of their other bonuses is too much. )
As for how to heal an undead, I agree that it shouldn't be quite as easy as a living character. Some people have suggested poison, but I'm not sure about that either. In D:OS 1, poison only worked on zombies, not skeletons. Poison is also pretty common. But if I take out poison, and if you don't want the corpse-eating healing method, all I can think of is some kind of life-leech skill. That could be used on party members who would be able to heal normally.
Well, actually I do have another idea - I suggested an active skill:
Undying Will (Active): This skill has a duration of three turns, and if you die while it is active, you automatically resurrect to 50% HP. 8 Turn cooldown or once-per-combat.
If you time its use correctly, you'll die, but be restored to 50% health immediately. It's a bizarre method of healing, I grant you, but it does fit with the "implacable man" style, and it does make tactical considerations of when to use the ability more important.
Although I still do think the corpse-eating method could be workable.