Nightpoint.io is an awesome survival game. Graphics are pretty simple, but it looks very nice. Your main goal is to survival, everyone will try to kill you – zombies, humans. So you need to get XP as faster as you can to become stronger. Every level up will give you points to increase such abilities as movement speed, max health, accuracy, and health regeneration.
Also, you can with every next level get a better weapon. XP you can receive from killing zombies and humans. The game is pretty addicting, try it!