It's called a RTS (Real Time Stratagy) game ... Top down view and commanding your troops. Warfare Incorporated is probably the best there is (In my opinion)
Heavy Mach 2 isn't a RTS but controls like one, it's more action You should check out some videos. http://www.youtube.com/watch?v=_z3haQbSNNU I haven't kept up with RTSs on the iphone so that all I know.
I'll throw another vote for Warfare Inc. It's a pretty good RTS game, and it has a huge amount of downloadable maps/levels created by the community. Apparently it is a game that has been on a variety of mobile platforms for years (I think going back to the older Palm OS and Windows Mobile platforms) so there are hundreds of levels to download.