Here is the full list of all 57 It came from space, and ate our brains achievements.
Finish the first six levels on medium.
Finish block ship on any difficulty.
Use the searchlights 5 times.
Finish block launchpad on any difficulty.
Place 15 mines.
Finish block scrapyard on any difficulty.
Place 5 turrets.
Staying alive while other players are waiting to respawn.
Use the shield 5 times.
Finish block suburbs on any difficulty.
Kill 10000 aliens.
Kill an enemy close to a player with one health.
Finish block industrial on any difficulty.
Finish block navy on any difficulty.
Finish the first six levels on easy.
Finish block planet on any difficulty.
Reach 75x multiplier.
Finish block crash site on any difficulty.
Kill 7 aliens at once.
Buy all rocketlauncher upgrades.
Finish block countryside on any difficulty.
Reach 50x multiplier.
Buy all laser upgrades.
Pick up 100 upgrades dropped by the S.W.A.T. Drone.
Buy all shotgun upgrades.
Finish block highway on any difficulty.
Buy all plasmagun upgrades.
Kill 1338 crawlers.
Finish block city on any difficulty.
Buy all machinegun upgrades.
Kill 1000 aliens.
Finish block hospital on any difficulty.
Die for the first time.
Buy all pistol upgrades.
Reach 25x multiplier.
Died 123 times.
Finish the first six levels on hard.
Finish the first six levels on insane.
Kill 100000 aliens.
Shoot 95471 times.
Make 25.000.000 amount of Coins in total.
Finish 1 multiplayer game on insane without dying.
Finish 3 multiplayer games on insane without dying.
Finish 6 multiplayer games on insane without dying.
Finish with the highest score in a multiplayer game.
Finish with the highest score in a multiplayer game 10 times.
Revive 5 people using medkits.
Complete all Campaign levels on Easy
Complete all Campaign levels on Medium
Complete all Campaign levels on Hard
Complete all Campaign levels on Insane
Complete Rooftops (Campaign) on any difficulty
Complete Clinic (Campaign) on any difficulty
Complete Alleys (Campaign) on any difficulty
Complete Sewers (Campaign) on any difficulty
Complete Riverside (Campaign) on any difficulty
Complete Cave (Campaign) on any difficulty