xbox360-TimeShift

Play as Dr. Aiden Krone
Enter the options menu, select "Multiplayer", "Model", then press Left to highlight Dr. Aiden Krone. Press Y, then enter "RXYMCPENCJ" as a code to unlock the Dr. Aiden Krone skin in Multiplayer mode. -From: vitruvian_soulless

Low gravity, jump higher, and run faster
While playing in Single Player mode, select "System Link" at the main menu, then "Host" a game. Select any game type. Set the gravity to "Very Low", jumping to "Very High", and movement to "Very Fast". Host the game, and it will fail. Return to the main menu, then select Single Player mode. The settings from system link will continue into your single player game.

Defeating the final Boss
In the battle with Dr. Krone's gigantic Sentinel, when you destroy one of his guns with the Pulse Gun, Krone will send artillery raining on your roof. In order to escape this barrage, slow time, and go into the far right corner. Face the wall and look up at Krone's Sentinel. Jump up on the platform. Keep running to the right into the corner. You will take no damage while in that corner. This works for all three barrages.

Achievements
Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Alpha District - Casual (10 points): Complete Act 1 "Alpha District" on Casual difficulty.
The Stronghold - Casual (10 points): Complete Act 2 "The Stronghold" on Casual difficulty.
The Forgotten - Casual (10 points): Complete Act 3 "The Forgotten" on Casual difficulty.
Munitions Plant - Casual (10 points): Complete Act 4 "Munitions Plant" on Casual difficulty.
Airborne - Casual (10 points): Complete Act 5 "Airborne" on Casual difficulty.
Alpha District Revisited-Casual (40 points): Complete Act 6 "Alpha District Revisited" on Casual difficulty.
Alpha District - Skilled (15 points): Complete Act 1 "Alpha District" on Skilled difficulty.
The Forgotten - Skilled (15 points): Complete Act 3 "The Forgotten" on Skilled difficulty.
Munitions Plant - Skilled (15 points): Complete Act 4 "Munitions Plant" on Skilled difficulty.
Pickpocket (10 points): Swipe 10 weapons out of enemy hands using Time Powers.
All Fall Down (10 points): Kill 3 enemies at one time during Time Stop.
Look What I Can Do (5 points): Walk on water using Time Powers.
Disarmed! (15 points): Shoot 5 weapons out of enemy hands.
Get It Off Me! (5 points): Remove a stuck Clutch Grenade using Time Powers.
The Stronghold - Skilled (15 points): Complete Act 2 "The Stronghold" on Skilled difficulty.
Airborne - Skilled (15 points): Complete Act 5 "Airborne" on Skilled difficulty.
Alpha District Revisited-Skilled (55 points): Complete Act 6 "Alpha District Revisited" on Skilled difficulty.
Alpha District - Elite (20 points): Complete Act 1 "Alpha District" on Elite difficulty.
The Stronghold - Elite (20 points): Complete Act 2 "The Stronghold" on Elite difficulty.
The Forgotten - Elite (20 points): Complete Act 3 "The Forgotten" on Elite difficulty.
Munitions Plant - Elite (20 points): Complete Act 4 "Munitions Plant" on Elite difficulty.
Airborne - Elite (20 points): Complete Act 5 "Airborne" on Elite difficulty.
Alpha District Revisited-Elite (70 points): Complete Act 6 "Alpha District Revisited" on Elite difficulty.
Beginner's Luck (15 points): Complete a level without dying on Casual difficulty.
That Guy Is Swift (25 points): Complete a level without dying on Skilled difficulty.
Death-Proof (35 points): Complete a level without dying on Elite difficulty.
You're It (10 points): Tag 15 enemies with Clutch Grenades.
TimeShift Veteran (25 points): Play 100 multiplayer games.
TimeShift Champion (50 points): Win 100 multiplayer games.
…Is On Your Side (25 points): Kill 50 opponents in Time Grenades or Time Fields.
Did I Do That? (30 points): Score a Fury Kill.
Berserker (30 points): Go on a Reaper Spree.
MVP (20 points): Capture 25 flags in Capture the Flag.
Yoink! (20 points): Retrieve 50 flags in Capture the Flag.
Are You Cheating? (20 points): Score 30 headshots with any weapon in multiplayer games.
Bullets Are Expensive (20 points): Kill 25 opponents with melee attacks in multiplayer games.
Have It Your Way (10 points): Host and complete 10 games with custom presets.
Very Gracious (15 points): Host a dedicated server for 48 hours total then quit.
I Don't Rent, I Own (25 points): Win a Ranked Deathmatch game by at least 5 kills.
King Me! (25 points): Win a Ranked King of Time game by at least 5 kills.
Not Even Close (25 points): Win a Ranked 1v1 game without dying once.
Keep Away! (25 points): Win a Ranked Capture the Flag game without the other team capturing your flag.
Nuclear Winter Wonderland (25 points): Win a Ranked Meltdown Madness game by at least 30 seconds.
The First of Many (10 points): Win a Ranked match.
Anytime, Anyplace (25 points): Win a Ranked match on every map.
Jack of All Frags (25 points): Win a Ranked match in every game mode.
Boy in the Bubble (30 points): Score 30 kills while trapped in a Time Grenade.
The following achievements require the bonus downloadable content:

DLC 1 Expert (25 points): Win ranked match on every map in DLC 1.
DLC 2 Expert (25 points): Win ranked match on every map in DLC 2.
Flag Snag! (25 points): Throw reverse grenade in CTF mode on enemy who carries your flag
Jump of the year! (25 points): Use time powers or time fields to prevent falling damage 3 times.
Master Miner--Crowned! (25 points): Get 25 kills using land or laser mines.
Off. Off. Damned Clutch… (25 points): Reverse clutch grenade from yourself 3 times in multiplayer.
Regicide Rules! (25 points): Kill king in King of Time mode 25 times.
Ride My Rockets! (25 points): Use rocket launcher 11 times to kill opponent while he is in the air. Low gravity mode will help.
You can't catch me! (25 points): Use your time shield to escape from any time field 25 times.
You won't even know how! (25 points): Throw reverse grenade when opponent is shooting you. Kill your opponent 3 times with his own shots.