By Ernest Hamilton , Updated Apr 16, 2021 09:57 AM EDT Close (Photo: https://pixabay.com/photos/children-win-success-video-game-593313/) It's pretty tricky to try to define .io games, but here's the most reliable and straightforward definition we came up with: an io game is a browser-based, free-of-charge, multiplayer, and casual game with relatively poor graphics. .io games became more and more popular in the last several years, and it's understandable. Multiplayer games usually cost money, and at least some of the most interesting titles from this category are pretty expensive: Tom Clancy's Rainbow Six Siege: up to 89,99 euros on Steam for the Ultimate Edition and 19,99 euros for the basic edition.