For startup Roblox, it pays to play with digital toys.

After closing a $150 million round of series F funding, Roblox is now valued at $2.5 billion, the company said Wednesday.

This isn’t the first big valuation for an open world game platform geared for kids. In 2015, Microsoft bought Mojang, maker of popular kids’ game Minecraft, for $2.5 billion.

“We think of this in terms less of a big number and more in terms of an emerging category for human interaction and co-experience,” said David Baszucki, Roblox’s founder and CEO.

Roblox, which was founded in 2004, is a platform where you can create your own games or join ones others have made. Roblox’s avatars look a little like Lego minifigs. There are more than 70 million monthly users, and users log about 900 million hours of engagement each month, according to Roblox’s website.

The funding round was led by Greylock Partners and Tiger Global with Altos, Meritech and Index Ventures also participating. Baszucki said plans for the future are, as you might imagine, growth.

“Ultimately we have the vision of expanding to a world wide platform that allows kids from the US to go on field trips to China and adults around the world to make friends from different walks of life and people who have different life experiences,” he said, and “to really help create a future digital civil society.”