Xbox One's backwards compatibility works because it's tricking your 360 games

"Last year, the team decided to tackle a feature that has been consistently at the top of your request list - and while we weren't sure if it was possible, today I'm pleased to announce Xbox One backwards compatibility." So went Phil Spencer. "Woo!" So went the crowd.

The announcement that 360 games would become playable on Xbox One ranks among the most popular moves Microsoft's made in years, which begs the question: why did it take so long? Speaking to Edge, Spencer explained the issue - the Xbox One needs to pretend to be an Xbox 360 to get the games working at all.

The 360's ability to play original Xbox games required every title to be tailor-engineered for 360 (thus the substantial gaps in the playable catalogue). For new-gen, the process is a little smoother, but takes some engineering sleight of hand:

"This time," said Spencer, "the team took the approach of effectively running the whole hardware OS that was running on the 360 hardware on the Xbox One. So when you boot the games, it literally boots up the operating system of the Xbox 360 - which is why you can play with Live and everything else. That was the most difficult thing."

While performance didn't turn out to be an issue - Spencer says the two console's chipsets are fairly similar - once you've convinced the 360 game that it's playing on a 360, you also need to convince the Xbox One that it's playing a One game: "That’s why you need to download the game. It's an Xbox One copy of the exact same game so that it shows up as an Xbox One game. That way [...] it shows the game ID and everything else."

Once the work was done, however, it's made the process of making 360 games compatible extremely simple. Microsoft now only needs the permission of publishers to get the games running - and the likes of EA and Ubisoft are already onboard, the latter even using the service to give old games away free as a bonus to Xbox One players.

The only downside? It's a solution so neat that it almost caused Spencer a problem, as he came closest to leaking the feature: "I noticed about a month ago… So I’ve been playing a lot of back-compat games on my Xbox One and people on Twitter were starting to be like ‘hey, why are you playing Banjo on the 360? Why are you playing Super Meat Boy on the 360?’. Then certain people started to whisper."

If you're curious, here's every Xbox One backwards compatible gamethat's set to launch with the service, as announced by Microsoft.