Here is the full list of all 24 Wholesome Slaughter achievements.
Kill 100 Bears
Kill 100 Unicorns
Kill 100 Wisps
Kill 100 Schwaplops
Kill 100 Pandas
Complete All Exterminator Achievements
Kill The Guide Fairy
Complete Level One
Complete Level Two
Complete Level Three
Complete Level Four
Jump 300 Times
Walk 666 Distance
Defeat The Final Boss
Heal For Over 1000 HP
Pickup Over 100 Ammo Crates
Complete The Campaign Without Dying
Get A Kill With Every Weapon
Find Every Secret Present
First Death
Die 10 Times
Complete The Campaign In 15 Minutes Or Less
Complete A Level Without Taking Damage
Find A Present