The first .io game was Agar.io. It was developed by Matheus
Valadares in 2024 and gained significant popularity through the 5️⃣ internet forum 4chan.
The game revolves around cells that grow by eating agar and consuming other players. A
few months 5️⃣ after its release, the game was acquired by Miniclip, and a new game genre
started to emerge based around the 5️⃣ humble .io domain extension.