Tomb Raider Underworld Cheats

Cheat Codes
Hold the Left Trigger, and enter the following codes. You receive the "checkpoint" sound if done correctly.

(Hold [LT]) [A], [RT], [Y], [RT], [X], [LB]: Invincibility.
(Hold [LT]) [Y], [A], [Y], [X], [LB], [B]: One shot kill.
(Hold [LT]) [X], [B], [A], [LB], [RT], [Y]: Show enemy health numerically.

Achievements
Complete each achievement to get the allotted gamerscore.

Climber (5): Execute a chimney jump of at least 2 wall kicks
Coastal Thailand Expedition (75): Coastal Thailand Expedition successfully completed
Dedicated Relic Collector (50): Find 3 Relics
Dedicated Treasure Collector (50): Find 100 Treasures
Grenadier (10): Kill two enemies with one grenade
Master Climber (10): Execute a chimney jump of at least 4 wall kicks
Master Grenadier (10): Kill three enemies with one grenade
Master Relic Collector (70): Find all 6 Relics
Master Roadkiller (10): Kill five enemies by running over them with the motorcycle
Master Speed Demon (10): Beat all three Speed Demon challenges
Master Survivalist (100): Complete the game on hardest possible settings
Master Swan Diver (10): In one adventure, swan dive off the three highest points over water in the game
Master Treasure Collector (60): Find all 179 Treasures
Mediterranean Sea Expedition (50): Mediterranean Sea Expedition successfully completed
Prologue (25): Complete the Prologue
Relic Collector (30): Find a Relic
Roadkiller (5): Kill an enemy by running over it with the motorcycle
Skilled Treasure Collector (40): Find 50 Treasures
Speed Demon I (5): Drive into Xibalba in under 45 seconds