It's a platformer about stealing gold from other players. You do this by navigating the traps that they have laid out in their dungeon. If you can survive them then you get their gold.
You also have to decorate your own dungeon with turrets, buzz saws, pitfalls, and a whole range of other deadly devices. If you don't then all that gold you steal will be, well, stolen back from you.
In our review of the iOS version of King of Thieves, we said that "[t]here's a great game here, but it gets a little lost in translation."
Still, you should be able to find something enjoyable about it. Plus, it's free to download, so it might be worth a try. Grab it on Google Play.