Brutal.io

There's a ball attached to the tail. Try to feed it with other green monsters. The bigger the ball, the more weight will it have, thus making you less mobile so you have to let it go at the right moment. You can see your score in the right hand side of the screen. It's very important that you climb as high as possible. It's not all that simple, but if you get accustomed to the game, you'll have fun for hours. So get right into it.