Don't expect Microsoft's acquisition of Activision Blizzard to suddenly mean the revival of Guitar Hero, or other classic franchises. These things take time, Xbox boss Phil Spencer has said, and should come from a genuine passion amongst developers.

Speaking on the Official Xbox Podcast, Spencer discussed his next moves now Microsoft formally owns all of Activision Blizzard's franchises - including Call of Duty and Crash Bandicoot.

Spencer is now off to meet Activision Blizzard's many teams in person, via a whistlestop tour of the company's studios. There, he said he will discuss what the teams want to work on.

"The first thing is to go spend time with the teams," Spencer said. "Because I just don't think a team working on something that isn't their passion leads to the best result. I might have my list of things from my memories and history that I want to see made again. Everybody will."

Spencer reflected on the vast vault of franchises Microsoft now acted as "custodian" of, and the need to only revisit these for the right reasons.

"I think not just about Activision Blizzard King, you add in Bethesda, Xbox's history, Rare, the amount of franchises we now have in our portfolio is kind of inspiring, it's daunting," Spencer said. "I feel we have to be a great custodian for the content that we touch. These are memories from people on different platforms, different decades.

"And I want to make sure that when we're going back and visiting something, we do it with our complete ability - a motivated team that wants to go work on something and make a difference, not just create something for financial gain, or create something for a PR announcement but not deliver on the final project. So I'm going to start with the teams and [find out] what they're passionate about."

In the future, Spencer said he was keen to use Xbox Game Pass as an oppurtunity to "revisit" certain classic franchises when the time was right.

"I think we've done an OK job at Xbox, I don't think we've done an A+ job of looking at our franchises and revisiting them," he said. "It's always a trade-off between what do you do that's new, [versus] going back and doing something. I do think with Game Pass we have the ability to maybe pick a couple franchises every year and almost do a 'revisited' - I just made up that term, it's not a brand...

"But I do think when you look across all the franchises that are part of our teams there's an oppurtunity for us to go back - even just to recognise the moment and what those things meant in gaming's history, and do something right with it, make it available to people through Game Pass... I think there's an oppurtunity. There's not a plan for that but there's an oppurtunity."

On the ability to go and do something more substantial - a full new game in a classic franchise, for example - Spencer said he was on board, if a developer had a strong desire to work on it.

"If teams want to go back and revisit some of the things we have and do kind of a full focus on it, I'm going to be all in on that, because I think there's an amazing trove of things we can touch again. It doesn't just have to be Activision Blizzard, when you look across the whole portfolio."

Elsewhere in the same interview, Spencer also discussed why it will take some time for Activision Blizzard games to join Game Pass, as well as the future of Call of Duty's timed exclusivity.