Diep.io

io is to kill other tanks with bullets that can vary in size, weight, and other factors, such as: bullet speed, bullet penetration, reload time (fire rate of the tank), health regeneration, movement speed, maximum health, or by ramming into other tanks with one's own body, which can also be upgraded. While upgrades can significantly improve a tank's standing against other tanks, smaller tanks can still outmaneuver one as a higher level tank, often in the form of buying bullet upgrades that can be shot towards one at high speeds or frequency. The browser version currently has 10 gamemodes—FFA (Free-For-All), 2 Teams, 4 Teams, Maze, Sandbox, Domination, Tag, Mothership, Breakout, and Capture the Flag. The goal of the game is to get on the top rank of the leaderboard and remain there for as long as possible.

When a player dies, they will recover some experience so they do not have to start from scratch. As a player levels up, their health gets a little larger, they get slower, and their body gets larger.

Reviews praised Diep.io as one of the best .io games alongside Agar.io and Slither.io, noting that the more in-depth tank upgrade system offered more replay value than other games in the genre. Android Authority described it as a spiritual successor of Agar.io. Conversely, Simon Reed of Gamezebo opined that the early stages of gameplay were slow and the gameplay loop was not compelling enough to keep players after the first several playthroughs, unlike Agar.io and Slither.io, saying that Diep.io is "lacking in a few key departments that just hold it back from greatness." He rated it 3.5/5 stars. Christian Vas of PCGamesN considered the team-based game modes to be the best.