Age of Empires: Castle Siege has been available on Windows Phone since 2014 and was a banner game for that platform. The developer, Smoking Gun Interactive, worked closely with Microsoft on the real-time strategy game and up until last week, you could only get it on Windows Phone and Windows 10. Last week it launched for iOS and now it looks like we Android users will get the game in March.
For those not familiar with Castle Siege, the game is a top-down tower defense style game where you select a civilization and begin building your empire. The game starts with plenty of step-by-step tutorials so even if you have never played AoE you will get the hang of it pretty quickly. Picking your civilization is important as each one has unique skills or technologies to it over others. If you have played in the past then again, this will feel familiar.