Earlier this month, a free to play spinoff of ARK: Survival Evolved was released called ARK: Survival of the Fittest.
It's essentially ARK, except for a survival arena game where 72 players fight to be the last man standing. You still do all of the foraging, hunting, crafting, and taming, but with a goal in mind... Killing the opposition. If you enjoyed H1Z1: King of the Kill or The Culling, you'll probably enjoy this game.
It's fairly difficult to run for lower end computers because it's horribly optimized, but hey, it's free.