Appearing on GameSpot sister site Giant Bomb’s E3 livestream tonight, Xbox boss Phil Spencer talked about Microsoft’s efforts in the PC gaming space. He started off by discussing one of PC gaming’s biggest players, Steam, and how Microsoft will release more of its games on it.

“I look at Steam today, it’s on an incredible growth trajectory. It’s a massive force in gaming; a positive force. I think it will be bigger a year from now than it is today. And five years later it will still be bigger again,” he said. “I look at Valve as an important [independent software vendor] for us on Windows. They are a critical part of gaming’s success on Windows. I don’t think Valve’s hurt by not having our first-party games in their store right now. They’re doing incredible well. We will ship games on Steam again.”

Also in the interview, Spencer stressed that, while Microsoft will put some of its future games on Steam (he didn’t say which ones), he is also committed to further building out Microsoft’s own Xbox store on PC. “I want to build a store; there’s no doubt about that,” he said.

Microsoft’s PC game releases on the Windows Store haven’t all gone too well, Spencer admitted.

“They all haven’t gone swimmingly. Some of them have gone well,” he explained. “Forza 6 Apex did well. Quantum Break wasn’t our best PC release. Killer Instinct did well on PC. Gears of War Ultimate Edition was OK–we definitely learned there.”

Speaking generally about Steam, Spencer added, “There’s going to be areas where we cooperate and there’s going to be areas where we compete. The end result is better for gamers.”

Some Microsoft-published games on Steam include Age of Empires II HD and Ori and the Blind Forest. One game that’s not there is Quantum Break–Valve isn’t missing out, Spencer said. “I think they’re doing fine without Quantum Break in their store,” he explained.

Additionally, Spencer addressed some of the concerns people, including Epic Games founder Tim Sweeney, have about Microsoft’s Universal Windows Platform.

“There’s still definitely concern that UWP and our store are somehow linked in a way that is nefarious. It’s not,” he stated.

Sweeney previously accused Microsoft of monopolizing PC development with the Universal Windows Platform. In the interview tonight, Spencer said he is on good terms with Sweeney, calling him a close friend and someone he speaks with frequently.

One other interesting thing to note from the interview was that Spencer revealed he demonstrated the new, more powerful Xbox Scorpio console to Valve higher-ups.