xbox360-Unreal Tournament 3

Play as Alanna (Necris)
At the custom character screen, press Y, then enter "phayder" as a code to unlock Alanna (Necris).

Play as Ariel (Iron Clad)
At the custom character screen, press Y, then enter "jihan" as a code to unlock Ariel (Iron Clad).

Bonus characters
Successfully complete the indicated task to unlock the corresponding character:

Lauren: Always select the second choice for all missions. Kill Lauren in Deathmatch in Chapter 2 of Campaign mode. Lauren will eventually become unlocked after a subsequent Deathmatch in that chapter.

Scythe: Always select the second choice for all missions. Kill Scythe in Deathmatch in Chapter 4 of Campaign mode. Scythe will eventually become unlocked after a subsequent Deathmatch in that chapter.

Matrix: Always select the second choice for all missions. Kill Matrix in Deathmatch in Chapter 3 of Campaign mode. Matrix will become unlocked after a side mission in Chapter 3 in that chapter.

Akasha: Kill Akasha in the final mission.

Loque: Unlocked after a Capture The Flag match in Chapter 5.

Damian: Unlocked in Chapter 4 of Campagin mode.

Kragoth: Unlocked in Chapter 4 of Campagin mode.

Malakai: Unlocked in Chapter 4 of Campagin mode.

Easy Damage Amplification
In the "Heatray" level in Multiplayer Deathmatch mode, after the Dark Walker drops, destroy it to get a Damage Amplification.

Special walls in Deimos map
There are orange and green looking energy/grainy appearing walls that you can walk through as well as shoot through. There are two of these orange walls that are circular in shape at the top of the map that allows you to reach a sniper rifle.

Open mic
Use the following trick to talk with your headset more effectively instead of holding D-pad Right. Hold D-pad Right, unplug your headset, reinsert your headset, then release D-pad Right. If done correctly, the microphone symbol should stay on screen, and you no longer have to hold D-Pad Right to talk.

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

Lock and Load (10 points): Complete Chapter 1.
Soldier's blood (30 points): Complete Chapter 2.
Does not compute (30 points): Complete Chapter 3.
Not in Kansas any more (30 points): Complete Chapter 4.
I'm not on a holy war (60 points): Defeat Akasha and complete the campaign.
Just business (30 points): Complete Chapter 2 in Insane.
Bag of bolts (30 points): Complete Chapter 3 in Insane.
Open war (30 points): Complete Chapter 4 in Insane.
Fear the Reaper (60 points): Defeat Akasha and complete the campaign in Insane.
I need some backup (10 points): Complete 1 mission in co-op.
Got your back (20 points): Complete 10 missions in co-op.
Thanks to all the little people (40 points): Complete a campaign in co-op.
I see how it is (10 points): Complete an Instant Action match in every game mode.
Untouchable (20 points): Reach 20 kills against a god-like bot in instant action without dying.
Like the back of my hand (40 points): Collect every power up on every map.
Spice of life (20 points): Play a match with every mutator, using only 1 per match.
Brain Surgeon (10 points): Get the "Head Hunter" award in 10 matches.
Don't taze me bro! (10 points): Get the "Combo King" award in 10 matches.
Goo God (10 points): Get the "Biohazard" award in 10 matches.
Pistolero (10 points): Get the "Gun Slinger" award in 10 matches.
Shard-o-matic (10 points): Get the "Blue Streak" award in 10 matches.
Hammerhead (10 points): Get the "JackHammer" award in 10 matches.
Strongest Link (10 points): Get the "Shaft Master" award in 10 matches.
Have a nice day! (20 points): Get the "Rocket Scientist" award in 10 matches and "Flak Master" award in 10 matches.
Big Game Hunter (10 points): Get the "Big Game Hunter" award in 10 matches.
Armadillo (10 points): Get the "Roadkill" award in 10 matches
Jack of all trades (10 points): Kill an enemy with every vehicle (except hoverboard).
Ace (10 points): Get the "Top Gun" award in 20 matches.
Deathwish (10 points): Get "Bullseye" (self-destruct to destroy an enemy) award in 20 matches.
Seeing Red (10 points): Have over 20 minutes of "Berserk Time".
Never Saw it Coming (10 points): Have over 20 minutes of "Invisibility Time".
Survival of the fittest (10 points): Have over 10 minutes of "Invulnerable Time".
Delivering the Hurt (10 points): Have over 20 minutes of "UDamage Time".
Hat trick (20 points): Achieve a Hat Trick in 10 CTF or VCTF matches.
Being a Hero (10 points): Return 100 Orbs in Warfare matches.
Flag waver (20 points): Completed 100 CTF matches played to at least 3 captures.
Thirty minutes or less (20 points): Complete 100 VCTF matches played to at least 3 captures.
Paint the town red (20 points): Complete 100 Deathmatch or Duel matches played to at least 20 kills.
Connect the dots (20 points): Complete 100 Warfare matches played to at least 3 points.
Serial killer (20 points): Get the "Killing Spree" award in 20 matches.
Sir Slays a Lot (20 points): Get the "Monster Kill" award in 20 matches.
Killjoy (10 points): End sprees in 20 matches.
Off to a good start (10 points): Get the "First Blood" award in 40 matches.
Lets get it on (20 points): Complete a multiplayer match in every game type.
Around the World (20 points): Win a multiplayer match on every map.
Get a life… (50 points): Get 200 kills in multiplayer on 50 different days.
Just warming up (10 points): Finish playing a "Versus" Ranked match.
Winning is the only thing (10 points): Finish with the highest points in a Ranked match.
Equal opportunity destroyer (20 points): Win a Ranked match in every game type.
Ranked Champion (50 points): Win 500 Ranked matches.