Here is the full list of all 23 Deadnaut achievements.
Rescue a captured Deadnaut
Kill a zombified Deadnaut
Kill 200 Type A enemies
Kill 100 Type B enemies
Kill 50 Type C enemies
Kill 10 Type D enemies
Complete a mission without destroying a room
Complete a campaign without destroying a room
Complete a mission without losing a Deadnaut
Complete a campaign without losing a Deadnaut
Complete the last mission of a campaign with a crew of cloned Deadnauts
Encounter the ghost of a deceased Deadnaut
Complete a campaign with a rating of Excellent or better
Teleport a Deadnaut to another room by entering a portal
Kill 15 enemies using hacked Sentinels
Complete a campaign featuring undead mutants
Complete a campaign featuring enhanced soldiers with firearms
Complete a campaign featuring portals and fast-moving aliens
Complete a campaign featuring madmen or horrors
Complete a campaign featuring incorporeal entities
Start and complete a mission with a single Deadnaut
Unlock all campaign modes
Complete a campaign on Extreme difficulty