You probably know that Achievements on the Xbox 360 are essentially static. Aside from new Achievements that might be added for a game by way of DLC, and maybe title updates, the Achievements programmed into the game from the time it is released are the only Achievements you’ll be able to earn. That is about to change with the Xbox One however.
With the X1’s tight integration with the cloud (specific details yet to be revealed), Microsoft has said that as more and more people play a game and earn the Achievements within it, the Achievements available might alter in response to how people are playing, or other events. To give an example, Dan Greenawalt of Turn Ten Studios (developers of Forza) has talked about the “I took an arrow to the knee” meme that originated with The Elder Scrolls V: Skyrim. Given the popularity of that particular meme a new Achievement could be added to Skyrim whereby if you do actually take an arrow to the knee, it will be unlocked.
Whether this idea of essentially “moving the Achievement goalposts” will appeal to all gamers is another question though. Many so-called “Achievement Hunters” pride themselves on being able to get 100% Achievement completion for a title. If they do that and then a whole bunch of new Achievements get added, some are likely to be pretty unhappy – particularly if they’ve moved on from the game to something else, or sold or traded it.