To grow means to eat something in order to implement its nutrients into yourself, making you bigger, stronger and fatter, of course. Agario is a game that captured the basic principle of growth and turned it into a constant battle of survival. The game was made by a 4chan user.
As mentioned above, Agar.io is an ever-growing game. You start as a small, colored blob on a grid filled with colorful, juicy balls. Each time you hover over one of those balls you grow a bit. The smallest ones are generated all the time and with a bit of skill and a lot of luck, you can grow considerably in a short amount of time. However, just like in life, there is always someone better than you, and bigger blobs can eat small ones. If you are unlucky and get eaten, the game is over and you have to start again. I have orbited one of the biggest blobs I’ve ever seen and it felt like comparing the sizes of the Moon and the Sun. Of course I got eaten, but it was amazing how huge a blob can grow. It is worth mentioning that the smaller you are, the more mobile and agile you are. When you gain some mass, and are chased by an even bigger blob, there are ways to sacrifice a piece of yourself in order to survive. For example, pressing space will divide yourself into two halves, propelling one of them to the location of your mouse cursor. That is an effective way of catching blobs that are more than half your size. The other option is to dispose of a part of your mass by pressing W. By doing that you become smaller but more agile and more likely to escape from the clutches of a giant blob.
Agario is an addictive game with a great interface; equal parts enjoyable and frustrating but nonetheless incredibly fun.