It's tough calling Warcher Defenders a «tower defense» game, as even though you're literally defending enemies from attacking your tower it's not the typical tower defense formula at all. (toucharcade.com)
Sybil: Castle of Death is a black comedy / horror themed strategy - tower defense game with a unique twist on the usual tower defense formula. (toucharcade.com)
Anomaly: Warzone Earth is an extraordinary mixture of action and strategy in a reversed tower defense formula. (anomalythegame.com)