Here is the full list of all 57 Unreal Tournament 3 achievements.
Complete 1 mission in co-op.
Complete Chapter 1.
Complete Chapter 2.
Complete Chapter 3.
Complete Chapter 4.
Defeat Akasha and complete the campaign.
Complete Chapter 2 in Insane.
Complete Chapter 3 in Insane.
Complete Chapter 4 in Insane.
Defeat Akasha and complete the campaign in Insane.
Complete 10 missions in co-op.
Complete a campaign in co-op.
Complete an Instant Action match in every game mode.
Reach 20 kills against a god-like bot in instant action without dying.
Collect every power up on every map.
Play a match with every mutator, using only 1 per match.
Get the "Head Hunter" award in 10 matches.
Get the "Combo King" award in 10 matches.
Get the "Biohazard" award in 10 matches.
Get the "Gun Slinger" award in 10 matches.
Get the "Blue Streak" award in 10 matches.
Get the "JackHammer" award in 10 matches.
Get the "Shaft Master" award in 10 matches.
Get the "Rocket Scientist" award in 10 matches and "Flak Master" award in 10 matches.
Get the "Big Game Hunter" award in 10 matches.
Get the "Roadkill" award in 10 matches.
Kill an enemy with every vehicle (except hoverboard).
Get the "Top Gun" award in 20 matches.
Get "Bullseye" (self-destruct to destroy an enemy) award in 20 matches.
Have over 20 minutes of "Berserk Time".
Have over 20 minutes of "Invisibility Time".
Have over 10 minutes of "Invulnerable Time".
Have over 20 minutes of "UDamage Time".
Achieve a Hat Trick in 10 CTF or VCTF matches.
Return 100 Orbs in Warfare matches.
Completed 100 CTF matches played to at least 3 captures.
Complete 100 VCTF matches played to at least 3 captures.
Complete 100 Deathmatch or Duel matches played to at least 20 kills.
Complete 100 Warfare matches played to at least 3 points.
Get the "Killing Spree" award in 20 matches.
Get the "Monster Kill" award in 20 matches.
End sprees in 20 matches.
Get the "First Blood" award in 40 matches.
Complete a multiplayer match in every game type.
Win a multiplayer match on every map.
Get 200 kills in multiplayer on 50 different days.
Win 500 online matches.
Grab 200 points worth of betrayal pots.
20 successful retributions against a betrayer.
Deliver 50 skulls in one score in Greed against adept or higher skilled bots.
Score 500 skulls in Greed.
Become a titan 20 times.
Become a Behemoth 10 times.
10 kills with every Titan weapon in one Titan transformation.
Use the Slow Field power-up for over 10 minutes total.
Get 100 kills with the Eradicator.
Kill 10 people with spidermines in deathmatch.