VioletZer0 said:
I've seen some pretty neat morality systems.
Most notably, Demon's Souls ''morality'' system affected how demonic a world became. The more demonic a world becomes, the stronger the mobs are. But you get more items and souls. Of course, you could make it less demonic and make the enemies weaker. But you miss out on several good items.
I don't think World Tendency is really a morality system, more like a reward/punishment system for playing well or poorly. I guess you could say repeated suicide a moral choice but you're not hurting anyone except yourself, and not even yourself really.
Demon's Souls also applies the black/white tendency system to your own character though, which works as an awesome morality system. It's simple and hugely effective:
Killing evil phantoms (players or hard-to-meet NPCs) makes you good... being good gives you more HP and attack power as a soul or blue phantom, which in turn makes it easier to be helpful in multiplayer or get through areas on your own without using revival items. Simply put, it's in your best interests at that point to continue being good.
Killing sane people and good phantoms (most NPCs, or invading other players) makes you evil... you get the reverse of the HP bonus from being good, and a big damage bonus when invading other people's games. Thanks to the reduced HP getting anywhere in your own game pretty much requires you to be using your human body... and when you need to revive yourself, you really suck as a helpful phantom so the easier (and more awesome) way to do it is invading another player and making sure they die. In short, you're better off being evil.
What's a little wierd, according to western morality at least, is that "good" is the easier choice... helping people is easier XP especially because of slaying invading phantoms. Staying evil takes constant effort because killing invading phantoms is pretty much a necessity and keeps pushing your character towards good.