Dictator Defense sells itself as a Tower Defense game with a difference. It's kinda like a hybrid between Command & Conquer and tower defense games in general. The game manages to pull it off but is overall a little easy.
The game plays in portrait mode (although loads in landscape?!) and just uses touch controls. As with all tower defense games, you have a base to defend and this is located at the bottom of the screen (the enemy base is at the top). Initially you can only deploy machine gunners and money banks. Money banks cost $50 but return $30 every so often (easy tip for the later levels - line your back rows with these banks as quickly as possible).