The goal is simple - move around the map and destroy other players while improving and upgrading your tank. Although this game may seem simple, there are different aspects like the upgrades and the map. There are a number of tank classes available, each with different weapons. Weapon choice is important and should be modified according to your play style. Players can also upgrade 8 different stats - health regeneration, max. health, hull damage, bullet speed, bullet penetration, bullet damage, reload and movement speed. Think carefully about which upgrades to use as you only have a limited number to use. A player may want to concentrate on bullet damage and speed, for example, to give more firepower. Alternatively, the player could concentrate on health and regeneration to improve their survivability.
There are also countless game modes available. The main mode is free for all - every player for himself. Try different game modes and see which one suits your play style.
Diep.io is available as a web browser game (HTML5), as an Android app, and as an iOS app.