Here is the full list of all 23 Undead & Beyond achievements.
Create your First Undead
Create 50 Undead
Enrage 10 Undead
Create a Volatile Undead
Create a Perfect Undead
Reach Level 2 of Biohazard
Reach Level 5 of Biohazard
Reach Level 10 of Biohazard
Escape the Containment Area
Escape the Laboratory Area
Kill Everyone in the Level
Create 100 Undeads
Enrage 20 Undead
See the game over screen for the first time
Have a Perfect Undead Kill 5 Humans
Create 30 Enraged Undead
Die 10 Times
Have Undeads Kill 100 Guards
Kill 50 Humans by Yourself
Create 20 Perfect Undead
Create 20 Volatile Undead
Have a Sprider Drone revive 5 Undead at the Same Time
Kill 3 Guards at the Same Time with the Explosive Drone