Rare’s online pirate game “Sea of Thieves” beats its targeted sales numbers on day one thanks to Xbox Game Pass and streaming services like Mixer and Twitch, Rare producer Joe Neate recently told USgamer.

“We beat all of our sales numbers that we had planned,” Neate said. “We literally — I won’t go into what specifically our sales numbers were because that’s confidential — but … we had a target to hit by the end of June, which we hit in day one of sales. It was fascinating because we were the first [Xbox first-party offered day one on Game Pass]. And, like, for the most part you kind of never want to be the first. You want to learn from someone else on things like that.”

Xbox Game Pass is a subscription service that lets Xbox One owners play older titles, and new exclusives, for $9.99/month. It officially launched on June 1. While it definitely gave “Sea of Thieves” a boost, Neate said streaming and content creators were the biggest contributors to the game’s success. “You could see it almost just in terms of when people were streaming, the number of streamers, the number of people viewing and all that stuff correlated to our playerbase,” he said.

“Sea of Thieves” is currently the fastest-selling first-party new IP on Xbox One, as well as the best-selling first-party title on Windows 10. It reportedly gained more than two million players in its first week. More than 100,000 people streamed the game during launch week, Rare said, resulting in more than 10 million hours watched during that period.

But, it hasn’t been smooth sailing for the pirate adventure game. Many called it fun, but shallow. Rare is working to address its lack of content, though. It recently launched the game’s first major DLC called The Hungering Deep. A second expansion, Cursed Shores, arrives in July. A third, Forsaken Shores, launches in September.