Updated March 30, 2021: New entries added

It's not always easy to pinpoint where a sub-genre comes from, but you definitely can in the case of the .io genre. It's right there in the name.

It all started with a web browser-based game called Agar.io, made by Brazilian developer Matheus Valadares. In this simplistic massively multiplayer game, players control a circular cell in an endless petri dish, and must gobble up smaller cells (controlled by other players) to survive and grow.

Thus was the .io genre born. We've seen a whole flood of imitators since, all playing their own meta game of survival of the fittest.

These games are typically quite stripped back, and are often playable through a website and on smart devices.

The .io genre has grown to a considerable size, with dozens if not hundreds of games taking up Agar.io's mantle. Along the way this fledgling genre has spread its wings and adopted a range of other influences and gameplay mechanics.

With that in mind we thought now would be a good time to round up some of the best and most popular .io games on the iOS App Store. Is you favourite missing from our list? Let us know in the comments below.