Here is the full list of all 57 Kill to Collect achievements.
Complete the campaign as Ivan Ironfist.
Complete the campaign as Kate Katana.
Kill a friend with the Rocketlauncher
Complete the campaign as Shocking Shelly.
Kill an enemy with the last bounce of the laser disc.
Complete all chapters of the campaign in any way you like.
Complete the campaign as Riot Ray.
Kill an enemy in a factory shredder.
Kill 8 enemies with one Lazer Cutter.
Complete a floor using just x -attack (Dodge is still allowed)
Complete a "One Try" Challenge.
Kill three enemies in one bull rush.
Watch yourself being placed first on a leaderboard.
Kill a Vanguard with a whip
Hit 5 or more enemies at once with Kate Katanas Crackdown.
Complete a floor ( not tutorial ) in 90s or less.
Complete a (not challenge, not tutorial) bounty in 350s or less.
Kill 3 enemies with one use of Ironfists ultimate ability.
Complete a Repeatable Challenge
Gib one of every enemy in the game.
Have your turret kill a Bounty Target.
Land 50 consecutive attacks in a row without taking damage.
Hookshot 15 enemies.
Kill 3 enemies with one Proximity Mine.
Deploy 4 turrets in a fight
Blow 3 enemies up with a Grenade.
Kill 15 enemies with a Flamethrower.
Kill 4 or more with one rocket using the Rocket Launcher.
Revive a friend with less than 1sec left on the timer.
Strangle someone to death with the LazerWhip
Have an Artillerist die by his own grenades.
Kill a Defender with the Handcannon
Set fire to 3 enemies with one Incendiary Grenade.
Clear every challenge room in a bounty without dying.
Land 20 consecutive attacks in a row without taking damage.
Beat a Challenge Room without taking any damage.
Complete the campaign with Kate Katana on Hard difficulty.
Complete the campaign with Shocking Shelly on Hard difficulty.
Complete the campaign with Ivan Ironfist on Hard difficulty.
Complete the campaign with Riot Ray on Hard difficulty.