Clash of Kings is a real-time strategy game where you can build your own city, recruit and train an army, and conquer all the nearby (and not so nearby) land to expand your empire.
In Clash of Kings, the most important concept is that of the capital: the place where your empire begins. In it, you can find lots of different structures like barracks, libraries, stables, farms, and mines. Each of these fulfills a specific objective that lets you advance in one way or another.
The barracks, for example, have a very direct purpose: they let you recruit soldiers. Libraries, on the other hand, can provide longer-term benefits, like developing new technologies for your weaponry so you can fight your enemies with an advantage.
Once you secure your city's defenses and have a good army, you can launch an attack on the general map. From this Clash of Kings map, you can decide who or what to attack. Other player's capitals will be tough targets, but wandering monsters probably not so much.
Clash of Kings is a real-time strategy game and while it doesn't offer anything new on the genre, it's still a polished experience expressly designed for smartphones.