The secret achievement is playing the game for 3 hours. According to several people the achievement can be glitchy so if it does not unlock properly uninstall the game and re-install then play for 3 more hours. This is how my friend got the achievement.
Achievement is called Fan and only counts in-game hours not idle time at all
[Completions: 4 | Retail 360: 1 | XBLA: 2 | XB1: 1]
Last edited by KillerBEA; 01-21-2011 at 04:50 AM.