NiGHTS into Dreams...
At the title screen, press Left, Right, X, B, A, Y, RB, RT, Down, Up, LB, and LT in that order. If done correctly, you'll get a confirmation that everything in the game has been unlocked, though save data, achievements, and posting to leaderboards will be disabled until you restart the game from the Xbox Dashboard.
|Left, Right, X, B, A, Y, RB, RT, Down, Up, LB, LT||Unlock Everything|
Contributed By: ValocDarkmyre.