Roblox is launching a new type of ad that, if watched, will give players things like in-game currency and power-ups, according to an announcement from the company.

The full-screen video ads, called “Rewarded Video ads,” can be up to 30 seconds long. The ads will be available to buy programmatically “via Google’s advertising solutions and direct buying (Direct IO) in the coming weeks,” Roblox says.

Owners of Roblox experiences must be at least 18 to show ads, and only public experiences are eligible, according to a page on its creator hub. Roblox says it only shows ads to players that are 13 and older.

The new ads are part of an expansion of Google’s “Immersive Ads” format. Google writes in a separate announcement today that they can show up as “a billboard ad you see driving through a virtual city or an ad on the big screen during a virtual football game.” The company claims these ads “blend naturally into the game environment.”

Roblox says it will start selling other ad formats through Google’s platform in the coming months, including billboards and entire rows on the Roblox home page.