Microsoft had earlier announced an overhaul to the Xbox Live achievement system. Spokesperson for the company Major Nelson has explained the new achievement system for the console on his blog. According to Nelson, the new achievement system is broken down into two categories—the traditional achievements that we have right now and special challenges.
The first category, Achievements, will work like it has been working so far, albeit with a few key differences. The developers can add new achievements to the game at any time by using cloud-based updates. Earlier, this could only be done by adding new DLCs to the game. There can now also be more emergent achievements that are more dependent on how people play games.
The ability to add achievements on the fly could be a great boon to gamers as well as developers
“For example, let's say a certain game is known on community forums to have a fun little sub-game of kicking chickens,” Cierra McDonald, Program Manager of the Xbox Live Achievements service, wrote. “Wouldn't it be amazing if the game developers noticed the community enjoying an unintended aspect of the game and creating a challenge around it, with a reward to boot?”
Challenges are a new addition to the achievement system and aren't necessarily permanent. These challenges can be made unlockable for a small amount of time, or they can be unlocked for getting certain achievements over multiple games. There can also be challenges that are unlocked by an entire community instead of a single person. An example of this is getting a million kills in a shooter; a goal which an entire community can work towards. Challenges can also be unlocked for non-gaming things, like watching a certain movie.