TouchGen writes: "Zombies, zombies and even more zombies is what you get in Zombie Attack! Second Wave. Second Wave is the sequel to the original Zombie Attack! released a year ago. The Zombie Attack! games are tower defense games with a definite own twist. Actually there are two major differences between Zombie Attack! and the million other tower defense games:
You control the survivor, and towers can only be built and upgraded by the survivor.
The cost of towers and upgrades aren't fixed but increase the more towers and upgrades you have. This forces you to really plan your tower coverage as you can't sell towers, and a poorly placed tower increases the cost of the next tower you need to build."