Second Sight Cheats for GameCube

Earth Impact Mini Game:
The Reliance mini-game is hidden on level 8 of the Reliance level. Go to the building on the right and enter it through the vents. At the room where a guard is playing one of the Arcades kill him and use the Arcade he was playing. The games High scores are tracked in your statistics menu and when you have unlocked this mini-game you will always be able to play it by pausing the game.
X-Space '92 Mini Game:
In the Madness level there is a hidden floppy disc which you can use on any computer on the level to play (the nearest computer to the disk is the reception computer). To get to the disc you have to go just past the reception desk section then through to the right and in the center of the corridoors with all the mental patients there is a room. Inside the room is the shotgun and on top of one of the shelves is the disc. You will have to use Telekinesis to reach it. The high scores are tracked in your statistics menu.

When you have beat either the Preparation level or the game you can go to Stark's training arena via Level Select by choosing it in the Preparation Difficulty menu. The training area is behind the gate you always go to in the end of the other training missions. This mission is harder than before, aim for the snipers and security cameras first then check around corners. There are about 15 to 20 enemies and a total of 4 cameras.

Here's one fascinating glitch I accidentally found, it's in the "Conspiracy" level I think(level in a building with a laser wall, men in black, and maids.). To do this trick, simply hide on a wall or in the bathroom, someplace a bit less conspicuous, use psychic ability Projection, go out and find a guard or a maid, and then possess them by having your glowing blue light walk up to/on them and press A. Where you want to go is, at the beginning of the level(with the guy at the computer you freaked out and killed during the cutscene), go down the left corridor and there're two guys playing some weird "E" word game behind a laser wall. Possess someone, go around so you're behind the wall(the right corridor from the start), and you'll see two elevators. Simply waltz up to one, press the button, and, if you have enough time and psi energy, enter the elevator when it opens up and wait for the door to close with the person in it. After about a minute, the person will disappear. No, they didn't walk out (they don't normally), but they vanished completely! Seriously, my projection was once in the elevator with a guy and he suddenly disappeared. Cool, huh?