Item Duplication (Cooperative Mode)
You can perform this cheat anywhere in the game, but it works best if you put it to use near a checkpoint and bench. You'll need to be playing with a friend, preferably one who is equipped with a headset so that you can communicate as needed. Start by giving your friend the items you wish to duplicate. After the trade is completed, exit out to the main menu and then immediately have the friend who received your loot save and quit from the pause menu. The trick only works if you follow that precise order, and quickly. If you did it properly, both players should now have the desired items in their inventory.
When picking up an artifact, advance to the next location to go past a doorway. Once you have passed the door, let it shut and reopen. Now return to the location where you found the artifact and in its place you should find resources such as the semiconductors, tungsten, scrap metal, transoucer and health packs. You can repeat this trick as often as you like.
Unlock Retro Mode
To unlock Retro mode, you must complete the game while on "Hardcore Mode"
Log Collection Unlocks
You'll gain access to additional gear by collecting the various logs in Dead Space 3.
MK-II Overclocked Module Set - Collecting all Logs
Research Circuit Set - Collect all Text Logs
Comms Circuit Set - Collect all Audio Logs
Artifact Collection Unlocks
You can gain access to additional items for your Artifact Collection by finding artifacts, as indicated below.
MK-II Overclocked Tip Set - Collect all Artifacts
Flight Suit - Collect all Artifacts
EarthGov Circuit Set - Collect all EarthGov Artifacts
Unitologist Circuit Set - Collect all Unitology Artifacts
S.C.A.F. Circuit Set - Collect all S.C.A.F. Artifacts
Alien Circuit Set - Collecting all Alien Artifacts
Optional Mission Unlocks
You can receive special rewards for completing optional missions, as noted below.
MK-II Overclocked Frame Set - Complete all optional (including co-op) missions
Hostile Environment Suit - Complete all optional (including co-op) missions
Weapon Collection Unlocks
You can gain access to additional goodies by satisfying the corresponding conditions.
Crafter's Circuit Set - Collect all weapon parts
Deep Dig Suit - Collect all weapon parts
Builder's Circuit Set - Collect all blueprints
MK-II Overclocked Attachment Set - Collecting all circuits
Completing the New Game+ mode on the "Classic" setting will unlock devil's horns.
Complete the game on various difficulty settings to gain access to additional modes and content.
New Game+ - Completing the game once on any difficulty
Retro Mode - Completing the game in Hardcore Mode
Dead Space Legends Suit Set - Complete the game once
+3 CLP Circuit Set - Complete the game on Casual difficulty
+3 RLD Circuit Set - Complete the game on Normal difficulty
+3 SPD Circuit Set - Complete the game on Hard difficulty
+3 DMG Circuit Set - Complete the game on Impossible difficulty
Get On My Level (10 points) - Complete the game on any difficulty setting.
The Explorer (25 points) - Complete all optional missions.
Aren't You Thankful? (50 points) - Complete the game on Hardcore Mode.
Epic Tier 4 Engineer (40 points) - Complete the game in Classic Mode.
Survivalist (40 points) - Complete the game in Pure Survival Mode.
Gun Collector (25 points) - Collect all Weapon Parts.
The Professor (25 points) - Collect all Artifacts.
The Librarian (25 points) - Collect all Logs.
The Armorer (25 points) - Collect all Circuits.
There's Always Peng! (50 points) - Find Peng.
My Buddy (10 points) - Retrieve Resources from a Scavenger Bot at a Bench.
Metal Detector (30 points) - Successfully deploy Scavenger Bots to 15 Resource Areas.
Strapped (10 points) - Craft a Weapon.
Circuit's Edge (10 points) - Add a Circuit to a Weapon.
EMT (25 points) - Craft a Large Med Pack.
Full House (25 points) - Craft a Weapon with 2 Tools, Tips, and Attachments with all Circuit slots filled.
RIG Master (50 points) - Fully upgrade your RIG.
Master Plan (25 points) - Create a Blueprint that needs at least 2000 resources worth of parts and Circuits to build.
From the Jaws (10 points) - Save your Co-Op partner from an execution by killing the attacker.
Share and Share Alike (10 points) - Use the RIG to give an item to your Co-Op partner.
Medic! (10 points) - Revive your Co-Op partner 10 times.
Ghosts of the Past (25 points) - Face all of Carver’s demons by completing all Co-Op only optional missions.
Architect (10 points) - Share a Blueprint with your Co-Op partner.
Axes High (20 points) - Kill 30 enemies using Fodder axes.
Payback (15 points) - Kill a Soldier by TK'ing a grenade or rocket back at them.
Go for the Limbs! (10 points) - Dismember 500 limbs from living enemies.
And Then We Doubled It! (10 points) - Dismember 1000 limbs from living enemies.
Slow Mo (10 points) - Kill 50 enemies while they are in stasis.
Blast Corps (10 points) - Kill 30 enemies with explosion damage.
Shootbang (10 points) - Kill 30 Soldiers with head shots.
Empty Chamber (10 points) - Kill 30 enemies using melee strikes or a melee Weapon Part.
Dropping Acid (10 points) - Dissolve 50 enemies with acid.
Electric Lawnmower (10 points) - Kill 30 enemies using an electrified Ripper blade.
Overpowered Healing (10 points) - Use quick heal to heal yourself 20 times.