Dead Space 2 Cheats

Elevator Action (Bronze): Knock off every Tripod during the Elevator Sequence
Epic Dismemberment (Silver): Dismember 2,500 Necromorph Limbs (single player only)
First Aid (Bronze): Use Quick Heal ten times (single player only)
Frozen in Time (Bronze): Kill 50 Necromorphs while they are in Stasis (single player only)
Fully Loaded (Bronze): Simultaneously have four completely upgraded weapons
Fully Outfitted (Bronze): Upgrade your RIG and Stasis completely
Going for Distance (Bronze): Impale an enemy and make him fly through the air for 17 meters - it must stick to the surface
Hard to the Core (Gold): Complete the game on Hard Core setting
Hornet's Nest (Bronze): Destroy the Tripod Nest
It's a Trap! (Bronze): Kill 20 enemies with Detonator Mines in a deployed state
Knock Knock (Bronze): Complete the Drill Ride
Lawnmower Man (Bronze): Kill 4 enemies with the same Ripper blade
Lightspeed de Milo (Bronze): Dismember the Lightspeed Boy Statue
Looking good (Bronze): Purchase the Advanced Suit
Made Us Whole (Bronze): Complete the game on any difficulty setting
Mission Impossible (Gold): Complete the game on Zealot setting
My Boom Stick (Bronze): Kill 6 enemies at once with Line Gun's Alt-Fire (single player only)
Necro Flambé (Bronze): Kill 50 enemies using the Flamethrower
One Small Step (Bronze): Get through the first Zero-G area
Operation! (Bronze): Snare the Shard with the Ishimura
Patient on the Loose (Bronze): Get your first Suit
Peek a Boo! (Bronze): Kill a Stalker with the Seeker Rifle while in Zoom Mode
Picking favorites (Bronze): Upgrade 1 Weapon completely
Powered Up (Bronze): Complete the Solar Array Puzzle
Romper Stomper (Bronze): Stomp 10 Containers
Shock Therapy (Bronze): Impale an enemy with the Javelin Gun and use its Alt-Fire to shock 3 others (single player only)
Shoot the Limbs! (Bronze): Dismember 25 Necromorph Limbs (single player only)
Shut Down (Bronze): Defeat the AI
Skewered in Space (Bronze): Impale an enemy into a Decompression Window to cause it to blow out
Taste of your own Medicine (Bronze): TK Impale a live Slasher to a surface using a Slasher's arm - it must stick to the surface
The Electrician (Silver): Collect 10 Semiconductors
The Engineer (Silver): Collect 10 Schematics
The Final Frontier (Platinum): Earn all Trophies in Dead Space 2
The Final Sacrifice (Bronze): Destroy the Marker
The Fugitive (Gold): Escape the Facility
The Graduate (Bronze): Win the fight at the School
The Librarian (Bronze): Collect 100 logs
The Nanny (Bronze): Kill 30 Crawlers without detonating them
The Sampler Platter (Bronze): Kill a Necromorph with every Weapon in the game (single player only).
Think Fast (Bronze): Kill 30 Necromorphs with Kinesis objects
Torment Me No More (Bronze): Kill the Tormentor
Vacuum Cleaner (Bronze): Decompress 20 Necromorphs without getting sucked out yourself

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

List of Online Unlockables
Through the online career you unlock these itmes:

Force Gun: Reach Level 11
Increased Damage (Seeker Rifle): Reach Level 50
Increased Magazine Size (Force Gun): Reach Level 29
Increased Magazine Size (Javelin Gun): Reach Level 44
Increased Magazine Size (Line Gun): Reach Level 25
Increased Magazine Size (Plasma Cutter): Reach Level 14
Increased Magazine Size (Seeker Rifle): Reach Level 33
Increased Weapon Damage (Force Gun): Reach Level 46
Increased Weapon Damage (Javelin Gun): Reach Level 57
Increased Weapon Damage (Line Gun): Reach Level 42
Increased Weapon Damage (Plasma Cutter): Reach Level 34
Javelin Gun: Reach Level 28
Line Gun: Reach Level 07
Seeker Rifle: Reach Level 17
Solid Army Green Suit: Reach Level 04
Solid Black Suit: Reach Level 13
Solid Olive Suit: Reach Level 16
Solid Red Suit: Reach Level 08
Tiger Camo Army Green Suit: Reach Level 45
Tiger Camo Blue Suit: Reach Level 41
Tiger Camo Military Suit: Reach Level 52
Tiger Camo Red Suit: Reach Level 49
Urban Camo Army Green Suit: Reach Level 23
Urban Camo Blue Suit: Reach Level 20
Urban Camo Military: Reach Level 32
Urban Camo Olive Suit: Reach Level 36
Urban Camo Red Suit: Reach Level 26
Visceral Games Suit: Reach Level 59
War Torn Suit: Reach Level 56

Refurbished Plasma Cutter
Start the game with save data from the original Dead Space on your console to unlock the Refurbished Plasma Cutter. It is only aesthetically different from the regular Plasma Cutter, designed more to look like the version found in the original Dead Space.

Refurbished Plasma Cutter: Start game with save data from Dead Space on your console, then pick it up at the first store.

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

Special Suits
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
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 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.
Soldier Suit: Beat the game on Hardcore Mode to unlock at Store