Browser-based multiplayer snakes!
Slither.io is a browser-based multiplayer game where you play as a snake (or maybe a worm? I'm not sure) trying to become the biggest of the bunch (while not becoming lunch). You accomplish this by eating pellets scattered around the map. Pellets are left behind as snakes move and when they die. Snakes die when their head bumps into another snake's body... and this is where things get interesting.