What is your favorite underrated online game you used to play in school?

Build Royale is a Top-down Shooter and Multiplayer video game with an emphasis on the Battle Royale genre, available to play on the Browser.

Diep.io is a multiplayer action game available for web browsers, Android, and iOS, created by Brazilian developer Matheus Valadares. Players control tanks and earn points by destroying shapes and killing other players in a 2D arena.