Here is the full list of all 83 Slime 3K: Rise Against Despot achievements.
Kill 3000 Ballerinas
Get a level 3 copy of Super Scytherang
Get a level 3 copy of Candy Bomb
Get a level 3 copy of Money Box
Kill 300 Bots
Get a level 3 copy of Coin Launcher
Beat level 10
Get a level 3 copy of Olive Gun
Kill 300 Mantraps
Beat level 9
Get a level 3 copy of Bananarang
Beat level 8
Kill 666 Maniacs
Beat level 7
Get a level 3 copy of Watermelon Launcher
Beat level 6
Beat level 5
Get a level 3 copy of Blaster
Beat level 4
Kill 1000 Stilt-Walkers
Get a level 3 copy of Nuggets of Darkness
Get a level 3 copy of Needle Shotgun
Get a level 3 copy of Fire Beam
Kill 300 Pain Lovers
Get a level 3 copy of Dark Side
Get a level 3 copy of Obedient Zombie
Get a level 3 copy of Random Nails
Beat level 3
Get a level 3 copy of Fiery Horizon
Kill 200 Shieldbearers
Get a level 3 copy of Supreme Shotgun
Get a level 3 copy of Shotgun
Kill 600 Laser Swordsmen
Get a level 3 copy of Rocket Launcher
Get a level 3 copy of Assault Rifle
Kill 666 Fire Mages
Kill 1 Wheelman
Kill 50 Fridge Men
Get a level 3 copy of Flashes
Get a level 3 copy of Scytherang
Beat level 2
Get a level 3 copy of Pistol
Kill 2 Watchers
Kill 10 Madmen
Beat level 1
Kill 100000 Newbies
Kill 10000 Bees
Kill 10 Thornies
Kill 2000 Martial Arts Masters
Kill 999 Black Swordsmen
Kill 5000 Doc Ocs
Kill 3000 Brains
Kill 6000 Specters
Kill 30000 Tomatoes
Unlock all Slime starting setups
Unlock every ability
Unlock every achievement!
Get a level 3 copy of Obedient Doc
Get a level 3 copy of Triangle of Darkness
Get a level 3 copy of Supreme Gun
Get a level 3 copy of Caliperang
Get a level 3 copy of Meteorite Satellites
Get a level 3 copy of Homing Loogie
Get a level 3 copy of Tiny Spring
Get a level 3 copy of Disco
Get a level 3 copy of "Heretic's Fork"