| Achievement | How to unlock | 
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|  | Defeat the Battlelord on the Hoover Dam.
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|  | Win air hockey with a score of 7-0 in the strip club.
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|  | Earn a 1,000,000 pinball score in SP.
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|  | Shoot down 20 alien fighters.
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| Beating the One-Eyed Worm
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|  | Blow up 5 enemy gunships or dropships.
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|  | Find all 3 helmets in the SP campaign.
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|  | Listen to all phone messages.
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|  | Complete the SP campaign on Hard Difficulty.
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|  | Unlock the secret closet at the end of the Forkstop.
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|  | Complete the SP campaign on Insane Difficulty.
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|  | Kill 10 aliens with environmental explosives.
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|  | Doodle something on the whiteboard in SP.
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|  | Kill 15 aliens with melee attacks while on steroids.
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|  | Kill 6 aliens with the forklift.
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|  | Get knocked down 10 times.
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|  | Carry the gold pistol through the whole SP campaign.
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|  | Discover all ego cap rewards.
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|  | Look at every page of a calendar in SP.
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|  | Get hit by 10 Pregnator bombs.
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|  | Complete the SP campaign on Normal Difficulty.
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|  | Win a game of Alien Abortion in the strip club.
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|  | Knock out the talent at the talk show.
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|  | Eat 10 pieces of food during the SP campaign.
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|  | Kill 30 aliens with headshots.
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|  | Drink all of the beers in the strip club.
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|  | Kill all of the catfish in the underwater level.
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|  | Complete the SP campaign on Easy Difficulty.
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|  | Defeat the Battlelord in Las Vegas.
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|  | Kill 15 aliens with the monster truck.
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|  | Watch the credits all the way through.
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|  | Put a Trip Mine on a live alien.
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|  | Drink beer while on steroids or vice-versa in SP.
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|  | Shoot down the blimp above the stadium.
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| Tosser... in the Literal Sense
 | Kill 10 aliens with tossed objects.
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|  | Kill 10 aliens with trip mines.
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|  | Find and steal a piece of poo.
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