No missable achievements (plus 62 unknown)
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Rescue professor Stein. So to say.
Complete any level in single player.
Kill at least 5 headless kamikazes in one explosion.
Squash 10 Hatchling spiders.
Secure the bird.
Rip 10 Juvenile spiders apart.
Decipher an Egyptian text.
Complete any level in cooperative with at least 2 players.
Remove 10 Gnaar eyes.
Kill an enemy using the Mutilator.
Solve the riddle of the Sphynx.
Tear off 10 Kleer heads.
Kill an enemy with a gib torn from another enemy.
Rip out 10 Rocketeer hearts.
Kill a Witch-Bride of Achriman.
Break 5 Arachnoid necks.
Kill the kicked enemy while it is still in the air.
Smash 20 Kleers with the Sledgehammer.
Power up the Timelock.
Kill 20 enemies with the Minigun without releasing the trigger.
Find Sam's classic outfit
Awake the Guardian of Time.
Break 10 Soldier necks.
Kill 5 Cave Demons while they're in air.
Gib 20 enemies from close range with a shotgun.
Rip Scrapjack's head off.
Blow a Major Biomechanoid into pieces.
Kill 3 enemies in one sprint with the Sledgehammer.
Use the Mutilator to surf after a Werebull.
Perform all possible finishing moves in the game.
Kill at least 3 enemies in one spinning Sledgehammer attack.
Complete a deathmatch game with at least 1 frag.
Earn a medal in Survival.
Pierce 5 enemies with one Devastator round.
Complete the single player campaign.
Complete the campaign in cooperative with at least 2 players.
Find the Vista secret.
Decapitate a Khnum.
Win a versus match.
Earn a gold medal in Survival.
Find at least 50 secrets in single player.
Complete the Jewel of The Nile single player campaign.
Frag 20 players with the Sledgehammer.
Make at least 3 kills in one Instant Kill match.
Complete a Beast Hunt match
Win one round in Last Man Standing game with at least 4 players.
Score a total of 10 points in CTF matches.
Complete the game in single player on unmodified serious difficulty.
Pick up at least 10 extra life items.
Win 10 deathmatch games.
Find all secrets in single player.
Complete the game in single player in half the estimated time on each level.
Win one My Burden match with at least 3 players.
Complete a Coin-op cooperative game on normal or higher difficulty.
Complete the game in single player without manually reloading, aiming or sprinting.
Pick up 100 gold coins.
Decipher all Egyptian texts.
Complete The Guardian of Time in single player on serious difficulty without dying or loading.