Ingress

Ten months after the collapse where mankind was annihilated in a war with monsters of unknown origin, a young man named Adam lives alone in an empty world. When one calm evening a man named Seth shows up, soaking wet, and claims to have come from a time where the world was normal. He was being vacated from his home town on a small boat when something big hit the boat causing him to fall overboard and into the deep. Only when he came back up, he found that the world was a different place. With this knowledge the two discover that there are portals in water that lead to different time continuum's. Through their journey they meet another individual named Noah and together are tasked to find the portal that leads to the continuum that they seek as vicious monsters mercilessly stalk them. A time continuum where the monster war ends... and we win.