slither.io

slither.io is a massive online multiplayer snake game. It has similar eat-or-be-eaten gameplay as in agar.io except with snakes.

Players start the game with the smallest length snake and the goal is to eat your way up the food chain and get the largest snake. The snakes are allowed to run over their own tail, but must avoid running into other snakes with their head. When players run into another snake they die, leaving glowing particles which the remaining snakes can then eat to grow. The longer a snake is, the more particles it will leave.

Players can move faster by holding down mouse button, but this causes the snake to slowly shrink and leave small particles behind. These short burst of speed can be used to cut off other players. This is different to agar.io because, with some skill and sometimes luck, even small snakes can corner and defeat bigger snakes, and then eat them for massive gains.