The Suit
You can obtain the military suit after beating "Dead Space" on any difficulty setting. When you start a new game, you can locate the military suit in your inventory. The suit itself will be labeled as a schematic. The suit is a level six suit, which means that it offers you better armor and protection than suits prior. You can obtain the level six military suit in all versions of the game, including the Xbox 360 version, the PlayStation 3 version and the PC version.
New Game Plus
After you defeat "Dead Space" on any difficulty setting, you'll be able to play in New Game Plus mode. This means that you can play the game again with all of the items you have earned -- including the level six military suit -- intact. However, you can't change the difficulty setting of the game: You must replay it on whatever difficulty setting you beat the game on the first time. If you beat the game in New Game Plus mode while wearing the military suit, you can replay the game on the "Impossible" difficulty setting while still wearing the suit. To do this, skip the end credits after you beat the game on New Game Plus mode and don't hit save. Start a new game, choose "Impossible" for your difficulty setting and you'll be wearing the military suit.
Xbox 360 Cheats
If you own "Dead Space" for the Xbox 360, you can activate cheats that either refill your oxygen within your suit or refill your stasis within your suit. During game play, hit "pause" and then press the "X Button," the "X Button," the "Y Button," the "Y Button" and the "Y Button," and you'll have full oxygen. Also during game play, press the "X Button," the "Y Button," the "Y Button," the "X Button" and the "Y Button," and your stasis meter will fully reload.
PS3 Cheats
If you own "Dead Space" for the PlayStation 3, you can activate cheats that will refill your oxygen within your suit, as well as your stasis and your kinesis. To refill your oxygen, press "pause" and then press the "Square Button," the "Square Button," the "Triangle Button," the "Triangle Button" and the "Triangle Button." To refill both your stasis and your kinesis, hit "pause" and then press the "Square Button," the "Triangle Button," the "Triangle Button," the "Square Button" and the "Triangle Button."