Activate cheats...
	Jewel Of The Nile: Achievement...
	Mental difficulty...
	Various Achievements...

While in the main menu hold down LT and RT while still holding them tap LB and RB rapidly and it will ask if you want to enable cheats. While in game pause and it should say :X cheats.

Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
Deathmatch Master (10 points)	Win 10 deathmatch games.
Flag Thief (10 points)	Score a total of 10 points in CTF matches.
Instant Killer (5 points)	Make at least 3 kills in one Instant Kill match.
Jewel of the Nile (20 points)	Complete the Jewel of The Nile single player campaign.
Look Ma, I won! (5 points)	Win a versus match.

Successfully complete the game under the Serious difficulty setting.

Complete the following achievements to unlock Xbox Live Gamerscore points.

Achievement	How to unlock
Are You Serious!? (30 points)	Complete the game in single player on unmodified serious difficulty.
Bone Crusher (5 points)	Smash 20 Kleers with the Sledgehammer.
Chain Explosion (10 points)	Kill at least 5 headless kamikazes in one explosion.
Classic Outfit (10 points)	Find Sam's classic outfit.
Co-op Master (10 points)	Complete the campaign in cooperative with at least 2 players.
Get the hell off my ride! (10 points)	Secure the bird.
Headsman (10 points)	Decapitate a Khnum.
Killer Jewelry (5 points)	Kill an enemy using the Mutilator.
Kung-fu Fighter (10 points)	Perform all possible finishing moves in the game.
Load of Scrap (5 points)	Rip Scrapjack's head off.
Look, it's a secret (15 points)	Find at least 50 secrets in single player.
Maintenance time (5 points)	Blow a Major Biomechanoid into pieces.
Mission completed (10 points)	Power up the Timelock.
Problem solver (10 points)	Solve the riddle of the Sphynx.
Serious Beginner (5 points)	Complete any level in single player.
Serious Sam (20 points)	Complete the single player campaign.
The doorman should wear a suit (10 points)	Awake the Guardian of Time.
Trick Shot (5 points)	Kill the kicked enemy while it is still in the air.
Wall of Bullets (5 points)	Kill 20 enemies with the Minigun without releasing the trigger.
Wanted Dead or Alive (10 points)	Rescue professor Stein. So to say.