I can help you though
X, A, B, DOWN, RIGHT, Y
God mode. Total invincibility to all attacks. You can just stand there and the aliens can't kill you. Heck, you could even put the controller down and they still can't do anything. You could even walk away from the Xbox and—crazy idea—talk to someone who's been sitting here for the past hour wondering if that was in fact an actual conversation she had earlier about going to the movies this afternoon and not just an incredibly realistic dream. In fact, you could come back to the game three hours later and you'd still have all your health. You could even come back to the game tomorrow—while a certain someone is working a 10-hour shift at Lane Bryant to pay the rent since someone else was recently "downsized" from Golden Swirl for "managerial reasons" that I'm sure were totally unrelated to his habit of napping in the service hallway—and you'd have the whole day all to yourself. Incredibly enough, Master Chief would be in fine, fine shape.
Do you know someone who did that?!?