Here is the full list of all 36 Spareware achievements worth 1,000 gamerscore.
Kill 128 enemies
Kill 256 enemies
Kill 1024 enemies
Kill 16384 enemies
Kill 65536 enemies
Die on Easy difficulty
Complete the Core on Casual
Complete the Core on Easy
Complete the Core on Medium
Complete the Core on Hard
Finish a level in 4 player coop
Complete a run without anyone dying in coop on Medium or higher
Reach level 8
Reach level 16
Reach level 32
Reach level 50
No friendly kills in a single level in coop
Defeat the Core level 10 times
Kill 5 enemies with a single mine
Don't take any damage in a level
Don't take any damage in a whole run
Complete the game with four players so none take damage
Kill ten enemies with a single railgun shot
Kill 20 enemies with one eBola shot
Kill an enemy with a bullet that has bounced at least 3 times
Kill 256 enemies with Flechette
Kill 256 enemies with Bolter
Kill 256 enemies with Railgun
Kill 256 enemies with Rocket Launcher
Kill 256 enemies with Grenade Launcher
Kill 256 enemies with Speargun
Kill 256 enemies with eBola
Kill 256 enemies with Shield Ricochets
Unlock the whole Scout-tree
Unlock the whole Juggernaut-tree
Unlock the whole Support-tree