Unlock Danger Room Missions: There is a total of 8 Danger Room missions to unlock. The first three are unlocked during game play but to unlock the other six you have to collect ALL the Sentinel files and Weapon X files for each character.
Achievements Complete the following tasks to get the corresponding gamerscore.
Xavier Institute Iceman - Gamersocre 0: Complete Iceman's training mission
Xavier Institute Nightcrawler - Gamerscore 0: Complete Nightcrawler's training mission
Xavier Institute Wolverine - Gamerscore 0: Complete Wolverine's training mission
Danger Room Iceman - Gamerscore 20: Complete Act 1 of the game
Danger Room Nightcrawler - Gamerscore 20: Complete Act 2 of the game
Danger Room Wolverine - Gamerscore 30: Complete Act 3 of the game