Agar.io is strangely very addictive

Agar.io is an online HTML5 multiplayer game where you control a circular blob, and your job is to eat all blobs smaller than you while avoiding circles larger than you because they want to eat you.  You control your blob with the mouse and have the ability to split yourself using spacebar, cutting you in half and shooting half of yourself, and poop out little blobs with W.

It’s very addictive and everyone should try it at least once.  It also shows minimal graphics can make good and deep gameplay.