Undead Citadel achievements

Finish level "Catacombs" (7)

Kill an enemy at 30m

Finish level "Runway" (5)

Finish level "Graveyard" (6)

Finish level "The wall" (4)

Finish level "The Maze" (8)

Finish level "Inner walls" (9)

Survive for more than 10 waves in the Horde mode

Finish level "Tower" (10)

Finish level "Bridge" (3)

Kill 500 undead enemies

Finish level "Entrance" (1)