BattleMaze.io, a game by GeeS.

You are trapped with other player(s) in a maze.

You have to color the room as fast as you can, in order to take the lead and gain power. You may be killed by a stronger opponent who colored faster…

The survivor (or the one with the largest colored surface at the end of the timer) wins!

Piece of advice: the more you kill, the stronger you become.