Here is the full list of all 31 Dark Zone Defense achievements.
Wound 1000 times
Beat Elizabeth In Dark Stage
Use HP regeneration for 20 times
Kill 20000 Monsters
Has more than 5,000 stars at the time of death
Successfully defend yourself 20 times with Iron Curtain
Beat Chaos
Get the end level of Dark Stage without using HP regeneration
Complete all normal levels unharmed
Receive 30 attacked from behind
Play the game 100 Times
Play the game 50 Times
Beat Boss W.Y.L 30K In Dark Stage
Beat Boss Mini In Dark Stage
Aquire the maximum vision from ability
Play the game 10 Times
Finish Huge Wave 3 times
Stay with the first rifle and aquire the Silver Bullets
Kill 3000 monsters
Complete 10 normal levels unharmed
Beat Elizabeth
Beat Boss W.Y.L 30K
Arrive At The 13th Level 3 Times
Get the end level of Noraml Stage without using HP regeneration
Beat Mini
Complete 6 normal levels unharmed
Has more than 2,000 stars at the time of death
Complete the tutorial
Kill 100000 Monsters
Beat Wolfram
Beat Wolfram In Dark Stage