When most people think of browser-based games, they think of Agar.io. In this MMO action game, players control a circular cell that hunts for smaller static cells to consume. Other players command rival cells against which you must compete for food – and if their cell is larger than yours, you risk becoming their food if they catch you. This is where things start to get interesting: the larger your cell, the slower you move.

So, what happens when you're too slow to consume cells but too small to absorb everything in sight? Cells can be split in half at any time, giving players two separate cells to control. Each cell can split up to four times, allowing players to avoid certain death when confronted with a massive foe. Agar.io’s highly addictive gameplay, in addition to its five unique multiplayer modes, make it one of the best io games to play with friends.

An unlikely internet sensation when it launched in 2015, Agar.io spawned an entire genre of spinoff “-io” games with trademark low-res graphics and free, free-for-all gameplay. Slither.io has since surpassed Agar.io in popularity, but Agar.io retains a core fanbase that has remained loyal for the past half-decade and more. Whether you want to jump back into the game for nostalgia’s sake or try it for the first time, be warned: You’re going up against cell-devouring veterans who will chew you up and spit you out, literally and figuratively.