CoolSnakes.io is a multiplayer, slither-snake, battle-arena game set in a flat, snowy landscape surrounded by walls. The player's goal is to grow a block-style snake or similar creature as large as possible by eating different colors and types of food that are also made of blocks.
The player can choose from a variety of snakes (blue racer, cobra, coral snake, corn snake, garter, green snake, king snake, milk snake, python, rat snake, salt marsh and sand boa). They can also select people, bunnies, a dragon and cityscape objects. Unlike similar games, they don't have to pay any in-game money to play one of these snake skins. Once the player creates a name, they're taken to the arena. They then direct their snake to slide around to eat food.
Cool Snakes complicates play with a couple of obstacles. As the snake grows, it slows down, but the game offers a temporary speed feature that's turned on with either an hourglass symbol or the controls. It also offers a shield symbol that provides a few seconds of head protection. If the snake hits another snake with its head without protection, then it dies and turns into different foods that other snakes can eat. If two snakes hit head on, they both transform into food.