Diep.io

Diep.io carried the successful .io game formula over into the tank-action genre. The 2016 game was created once again by Matheus Valadares, the author of Agar.io, and this time, instead of consuming cells, it offered players control of a tank that moves around an arena, destroys geometric shapes and rival players, and gradually upgrades itself with points earned.

The upgrade system is the core of the whole game – as experience accumulates, the player chooses a direction to specialize their tank in, from rapid-fire machine-gun turrets through sniper cannons to heavily armored variants with multiple barrels at once. This branching decision tree gives Diep.io an unusual strategic depth for an .io game, since choosing the wrong development path can practically doom a player against a well-built opponent in combat. At the same time, the controls are simple – mouse for aiming and shooting, keyboard for movement – so even a complete newcomer gets into the game quickly.

Visually, Diep.io stays true to the stark geometric style that Agar.io made famous – simple shapes, clear colors, and a clean arena where the battle for survival plays out. The combination of accessibility and a system of gradual specialization helped the game keep a loyal player base even after the first wave of interest in .io games in general had faded.

Why play it: For players who want more from .io games than just a chase – the tank upgrade system adds genuine tactical choice while fully preserving the simple controls.