I'm sorry, but if you came for a solution that is not what I'm really posting about. The solution itself is in the sub-title; "Earn every achievement." and this achievement will unlock.That is not the case. The achievement itself is glitched. I noticed that everyone here didn't have it and assumed it was glitched because they got the game and played it early on. A THQ employee on the xbox.com forums wrote on October 27, 2009, that they were aware of the problem:I finished the game yesterday (December 9, 2009) and the achievement did not pop. I contacted THQ, which I believe everyone should, and let them know I saw the post they made but wanted to know an ETA for the fix. I received a reply back a day later and they said that the developer has not yet given them a estimated fix date.So if you are a completionist, you might want to wait for this to be fixed as 900/1000 is the highest possible score for this game as of this date. Not the solution I know you came here for, but I hope the additional information is at least a little helpful.