In this viral farming simulator, players can plant seeds, harvest crops, earn in-game currency (Sheckles), unlock mutations ...

In just under two months, a Roblox user-created game called Grow a Garden has become a massive hit.

Like YouTube, Roblox started as an online stage for young creators. As the company grows toward 100 million active daily users, contributors are making big money selling games.

Last year, McDonald’s Hong Kong built a McNuggets Land game inside The Sandbox in which players sell McDonald’s food alongside, confusingly, co-workers who are nuggets.