This is kind of a rip off from WoW, but to me it's a good idea that gets you to keep playing a game, and that's putting in like small, trackable goals into the game.
Achievements can be from basic ones like leveling and missions (like the xbox live ones), to doing some weird stuff (which I cant really think of since im not sure how the game mechanics are exactly). Achievements would be trackable in your game or profile whatever to see what ones you have. Each one would come with small in game rewards like a title, novelty items, or other things for the harder to get ones.
It would also be pretty cool if Link Shells (or whatever they are calling it) could set up a limited amount of their own achievements to be trackable throughout the whole shell. It could even be set up to include an automatic reward system from a guild bank or whatever (which is something they should implement).
Anywyas, tell me what you think.