On Pause menu:

Code Effect

X(3), Y, X. +1,000 credits (one time only per playthrough)
X, Y(3), X(2), Y. +10,000 credits (one time only per playthrough)
Y, X(3), Y. +2 Nodes (one time only per playthrough)
X(3), Y(2). +2,000 credits (one time only per playthrough)
YXYXXYXXYXXY +5 Nodes (one time only per playthrough)
X(3), Y, X, Y. +5,000 credits (one time only per playthrough)
X,X,Y,Y,Y Refill you Oxygen
X,Y,Y,X,Y Refill your Stasis and Kinesis energy

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).

Unlockables

Backstory Logs Beat the game
Impossible Difficulty Setting Finish the game once on any difficulty
Military Suit Finish the game once on any difficulty

Unlockables - Achievements *Spoilers*

Complete each achievement to get the allotted gamerscore (1000)

A Cut Above (10) Kill 30 enemies with the Ripper
Air Alert (10) Zero-G Jump over 100 times
All Systems Go (20) Complete Chapter 3 on any difficulty setting
Armstrong (10) Shoot 50 objects using Kinesis
Autofire (10) Kill 30 enemies with the Pulse Rifle

Betrayed (20) Complete Chapter 11 on any difficulty setting
Big Spender (10) Spend 300,000 credits at the store
Brawler (10) Kill at least 30 enemies with a melee attack
Butcher (40) Dismember 1000 Limbs

Cannon Fodder (20) Complete Chapter 4 on any difficulty setting
Crackshot (5) Achieve a perfect score in the Shooting Gallery

Dead On Arrival (20) Complete Chapter 1 on any difficulty setting
Don't Get Cocky Kid (10) Survive the ADS Cannon with over 50% shield strength remaining

Epic Tier 3 Engineer (150) Complete the game on the hardest difficulty setting
Eviscerator (10) Kill 30 enemies with the Line Gun
Exodus (20) Complete Chapter 12 on any difficulty setting

Freeze (15) Use Stasis on 50 enemies
Full Arsenal (30) Own every Weapon in the game
Full Contact (10) Kill 30 enemies with the Contact Beam

Get off my ship! (15) Kill the Slug Boss
Greenhouse Effect (20) Complete Chapter 6 on any difficulty setting

Keeper of the Faith (20) Complete Chapter 10 on any difficulty setting
Kickin It (10) Escape from a Lurker's grab attack 10 times

Lab Rat (20) Complete Chapter 2 on any difficulty setting
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
Mindless Prey (30) Kill the Hive Mind

One Gun (40) Beat the game using only the Plasma Cutter

Pack Rat (10) Store 25 Items in the Safe
Playing Catch (10) Catch a Brute or Leviathan Pod using Kinesis
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 - Brute Force (15) Kill a Brute
Secret Achievement - Exterminator (15) Kill the Leviathan
Slugger (10) Kill the Slug Boss with more than 50% shield strength remaining
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