The fastest-growing video game in the world might just be a game within a game. Grow a Garden, labeled as an experience within Roblox, is skyrocketing in usage.

Roblox farming simulator Grow a Garden is eclipsing active player numbers achieved by some of the most popular games on across PC, mobile, and console – so what exactly is it?

On Saturday, more than 16 million people were planting seeds and collecting exotic pets within Grow a Garden at the same time. Many were not yet teenagers.