The io game genre started in 2015 with the release of a fun and addicting game called agar.io (which was probably inspired by a previous game called “Osmos”). Agario grew so fast that within months, it was already seeing several hundred thousand players worldwide, but it kept growing. What made this io game so unique was it’s very interesting style, of larger cells consuming smaller cells. Unlike most of the browser games of the past, which were mostly windowed, it was designed to be played in a fullscreen browser window, and was entirely multiplayer, which became a revolutionary concept. This set the stage for many of the other .io games that would hit the web in the months to come, and are still widely popular around the globe.