Diep.io is a broswer game
In Diep.io you control a tank with the goal of destroying other players in the server.
The best way to level up is to destroy other tanks, It's fun to troll people in the maze, its fun to play with your friends.

The best tanks are - the overlord, the fighter, the necromancer, pentashot, Hybrid . And more that I don't remember.
FFA, AND MAZE are the best mods for me.

So go and fight, make your own moments.
Diepio is one of the best games.