You have a main guy with stats to allocate every level, stat raises have a perceivable impact on your commanders abilities. Its got experience/levels, equipment slots for your defense equipment so you can't bring everything to battle. The difference in equipment is nice and the creatures you battle are differentiated well. The choices you make in just picking equipment to bring to battle can have a profound impact in defending the level. Very well designed and fun.
Its in Android and Apples market. If you like Defense games that I guarantee you will like this one.