Dead Space Cheats

Legend Teller (40): Collect 150 Logs
Live With The Hot Ones (10): Kill 30 enemies with the Flamethrower
Marksman (5): Dismember 20 Limbs
Maxed Out (75): Upgrade all weapons and equipment
Merchant (10): Collect 8 schematics
One Gun (40): Beat the game using only the Plasma Cutter
Pack Rat (10): Store 25 Items in the Safe
Pusher (10): Kill 30 enemies with the Force Gun
Ragdoll Check (5): Force an enemy into a Gravity Panel 5 times
S.O.S. (20): Complete Chapter 7 on any difficulty setting
Secret Achievement (10): Continue playing to unlock this secret achievement
Secret Achievement (10): Continue playing to unlock this secret achievement
Secret Achievement (10): Continue playing to unlock this secret achievement
Secret Achievement (10): Continue playing to unlock this secret achievement
Secret Achievement (15): Continue playing to unlock this secret achievement
Secret Achievement (30): Continue playing to unlock this secret achievement
Secret Achievement - Brute Force (15): Kill a Brute
Secret Achievement - Exterminator (15): Kill the Leviathan
Story Teller (20): Collect 75 Logs
Strange Transmissions (20): Complete Chapter 8 on any difficulty setting
Surgeon (20): Dismember 500 Limbs
Survivor (50): Complete the game on any difficulty setting
There's Always Peng! (15): Find the Peng Treasure
Tool Time (10): Kill 30 enemies with the Plasma Cutter
True Believer (20): Complete Chapter 5 on any difficulty setting
Wreckage (20): Complete Chapter 9 on any difficulty setting
Z-Baller (5): Complete Level 6 in Zero-G Basketball

Unlockables
Impossible Difficulty Setting: Finish the game once on Medium difficulty
Military Suit: Finish the game once on Medium difficulty

New Game Plus
Save after finishing the game. Then, load your CLEARED GAME save. You will start a new game on the difficulty which you previously beat the game with all you Items, all your upgraded equipment, including 10 extra power nodes, 50,000 extra credits, and the schematic for the Military suit (a LEVEL 6 SUIT that costs 99,000 credits).

Keep Military suit for Impossible difficulty
First, you must beat the game on New Game Plus mode, with the Military Suit bought and equipped, and save the game right before the last boss. After the game ends and the credits roll, skip them, and do not save the game when it asks you to. Instead, immediately start a completely new game on Impossible difficulty, and you will start the game wearing the Military Suit.