Top View Tower Defense: Fieldrunners -simply the best TD game out there http://itunes.apple.com/ph/app/fieldrunners/id292421271?mt=8 Horizontal Tower Defense: Ants Vs. Zombies -It is like PvZ but this one has Skills which you can use in game. And Upgrades (both passive and skill upgrades) which gives the game a new dimension. http://itunes.apple.com/us/app/ants-vs.-zombees/id498443077?ls=1&mt=8
