Press Up, Up, Down, Down, Left, Right, Left, Right, Start at the Cerebro Files menu.

Press Right, Right, Left, Left, Down, Up, Down, Up, Start at the Cerebro Files menu.

Press Down, Down, Up, Up, Right, Left, Right Left, Start at the Cerebro Files menu.

There are eight danger room missions. You unlock the first three as you play through the game. To unlock the other six danger room missions, you must collect all Sentinel files and Weapon X files with each character.