So bored that I spent my Sunday playing this game called agar.io. It is a massively mutiplayer online game that uses the concept of culturing bacteria. Players control a cell in a map which acts like a bacteria living in a petri dish. The goal is to engulf many smaller cells without being eaten by bigger cells. Every player will start of as a small cell. The bigger the cell, the slower the movement speed. Use mouse to control the direction and space bar to divide your cell.
The link of the website is agar.io
It uses C++ and JavaScript hence you do not need to worry about downloading it. It is also available on app store and Google Play by miniclip.