Operation: Tank Command 3 has you trying to take out waves of enemy tanks and avoiding the enemy. This is a sequel to Operation: Tank Command 2.

While the gameplay itself might seem very simple, it is also very chaotic so you want to spend some time with the engineer before going in. He offers research, primary and secondary weapons as well as upgrades and support. See screenshot #2 for an example of this.

There are a lot of levels (missions?) to go through and three difficulty settings. You can also adjust your keys and more under the options box. Overall what appears to be a simple side-scroller is hours of free gameplay. The app does not need to install, just run the executable.