I'd just like to note a couple of achievement models that I think are really cool, and that I wish more games would emulate, as well as invited discussion on what other achievement models might be useful.
1) Mass Effect: Achievements give you a bonus on future playthroughs, whether it's a new bonus power, or bonus XP. Simple, and effective especially in a game with so much replay value
2) Assassin's Creed 2+: Achievements give you option for bonus gameplay elements that are not really super big, but are nice. Whether it's a new skin or capacity for five extra throwing knives or whatever, I really like this system. The fact that it's tied into the irritating uplay system notwithstanding, I really like some of the stuff Ubi did with this model.
1) Mass Effect: Achievements give you a bonus on future playthroughs, whether it's a new bonus power, or bonus XP. Simple, and effective especially in a game with so much replay value
2) Assassin's Creed 2+: Achievements give you option for bonus gameplay elements that are not really super big, but are nice. Whether it's a new skin or capacity for five extra throwing knives or whatever, I really like this system. The fact that it's tied into the irritating uplay system notwithstanding, I really like some of the stuff Ubi did with this model.