Dead Space 2 Cheats

Shoot the Limbs! (10): Dismember 25 Necromorph Limbs (single player only)
Bouncing Betty (10): Kill a Cyst by catching its Mine and throwing it back
Skewered in Space (15): Impale an enemy into a Decompression Window to cause it to blow out
Hard to the Core (50): Complete the game on Hard Core setting
Clean Cut (10): Sever all three tentacles of a Lurker with one Line Gun Primary Fire shot (single player only)
Lawnmower Man (10): Kill 4 enemies with the same Ripper blade
Fully Loaded (50): Simultaneously have four completely upgraded weapons
The Sampler Platter (20): Kill a Necromorph with every Weapon in the game (single player only)
Lightspeed de Milo (10): Dismember the Lightspeed Boy Statue
Looking good (10): Purchase the Advanced Suit
Fully Outfitted (30): Upgrade your RIG and Stasis completely
Picking favorites (30): Upgrade 1 Weapon completely
The Engineer (10): Collect 10 Schematics
My Boom Stick (20): Kill 6 enemies at once with Line Gun's Alt-Fire (single player only)
Shock Therapy (10): Impale an enemy with the Javelin Gun and use its Alt-Fire to shock 3 others (single player only)
Collect Peng (20): Find the Peng treasure
The Librarian (10): Collect 100 logs
The Electrician (10): Collect 10 Semiconductors

Achievements for Dead Space 2: Severed DLC
Grind House (20): Severed: In the grinder room, cause an enemy to die in the grinders
King of the Hill (20): Severed: Defend the quarry platform until the door unlocks
Peng Me Again (20): Severed: Find the Peng treasure in Severed
Remember the Alamo (20): Severed: Kill 16 or more enemies in the final last stand combat sequence
Ship Shape (20): Severed: Take out the gunship within 30 seconds
The Betrayal (50): Severed: Complete Chapter 1
The Sacrifice (50): Severed: Complete Chapter 2
The Veteran (50): Severed: Complete on Zealot

Infinite Ammo Hand Cannon
If you beat the game in hardcore mode and upgraded the plasma pistol you should unlock the infinite ammo one hit kill hand cannon located in your first shop. Bang Bang! Pew Pew!

Multiplayer Skins
Complete the corresponding challenges to unlock the following skins for your human suit

Solid Army Green Suit: Unlocked by reaching level 04
Solid Black Suit: Unlocked by reaching level 14
Solid Olive Suit: Unlocked by reaching level 16
Solid Red Suit: Unlocked by reaching level 08
Solid Viral White Suit: Unlocked by killing another player with the suit equipped
Tiger Camo Army Green Suit: Unlocked by reaching level 45
Tiger Camo Blue Suit: Unlocked by reaching level 41
Tiger Camo Military Suit: Unlocked by reaching level 52
Tiger Camo Red Suit: Unlocked by reaching level 49
Urban Camo Army Green Suit: Unlocked by reaching level 23
Urban Camo Blue Suit: Unlocked by reaching level 20
Urban Camo Military Suit: Unlocked by reaching level 32
Urban Camo Olive Suit: Unlocked by reaching level 36
Urban Camo Red Suit: Unlocked by reaching level 26
Visceral Games Suit: Unlocked by reaching level 59
War-Torn Suit: Unlocked by reaching level 56
Zealot Suit: Comes with collectors edition of the game

Single Player Unlockables
Hardcore Mode: Beat the game on any difficulty
New Game+: Beat the game on any difficulty

Special Suits and Weapons
After finishing the game, you get two suits that gaves you 25% more resistance to any hit and if you have an old Dead Space save file you get the original Plasma Cutter wich cost 0 credist and can be found on any store at any time.

Arctic Security Suit: Beat the game on Zealot difficulty to unlock at Store
Dead Space 1 Plasma Cutter: Have an Dead space 1 Save File
Elite Advanced Suit: Schematic found in New Game + in Chapter 11 when the yellow lift reaches the top turn around and it is on the ledge between elevator and wall
Elite Engineer Suit: Schematic found in New Game + during Chapter 2, just before the first short outer space section.
Elite Riot Suit: Available at store during New Game +
Elite Security Suit: Schematic found in New Game + in Chapter 9 after you exit the tram, search over the railing.
Elite Vintage Suit: Schematic found in New Game + in Chapter 6 in the area you fight the tank before the end of the chapter.
Hacker Suit: Have "Dead Space: Ignition" save file to unlock at Store
Soldier Suit: Beat the game on Hardcore Mode to unlock at Store

Skip the Drag Tentacle in Chapter Five
If one pauses the game and restarts from checkpoint during the drag tripod encounter in the Church of Unitology, the entire sequence is skipped and the Pack encounter automatically begins.