Paper.io

This is probably the most fascinating IO game, which is fun, less predictable and grabs your attention a lot. The goal of the game, just like the first classic IO game, is to seize territory. The map you are roaming around is inhabited by other players, each trying to build up the territory as much as possible. Doing so looks easy: you're moving like a tank-shaped pixel on the screen, which can move freely in any direction, the full 360° range is free for your territorial requests. The point is that others also want to capture the land, so you will have to kill them, avoid being killed and stay on your ground to defend yourself. Also, you will seize their lands, protect yours and avoid finding your own trail as it will definitely kill you.