Here is the full list of all 18 Succubus With Guns achievements.
Get killed by slugs at level 1
Take training
Jump 5 times when the camera is in front of the character
Destroy slugs on first level
Kill 100 skeletons by sword
Kill 100 big guys
Die for 15 seconds on start level
Die 10 times on one level
Complete a level using only sword or melee
Kill 5 enemies with one shot
Find the sword
Finish level 1
Finish level 2
Finish level 3
Finish level 4
Finish level 5
Finish level 6
Finish game