Archipelago is one of those simple games where you basically send units to attach the enemy. Each of your "islands" produce planes. You tap your island, then another island, to send HALF of your planes from the origin island there. Islands can be yours, theirs, or neutrals. The idea is to conquer ALL the islands.
The interface on this one is a little iffy. I can't seem to make it send a single fleet from multiple islands. The game also crashes quite often. Even free, it's problematic.