SEGA have released a new free to play game on iOS and Android which mixes strategy and base building with real time combat sections.  It's called Kingdom Conquest II - a game that thrusts players into different classes of characters.  As we said the game is split between two sections, in the main strategy part of the game you'll be building up your base, collecting resources, training units, and conquering lands.  In the battle section of the game you'll face multi-level dungeons in 3rd person combat.  It's the latter sections that allow for some truly fun co-op gameplay, as these dungeons can be tackled with up to three additional players.