There has been a lot of back and forth on the so called "parity clause" on Xbox One, that allegedly forced developers to release their games on Microsoft's console day and date with other platforms. Xbox Division head Phil Spencer explained that there's no clause, and how it all works in an interview on Edge Magazine:

Edge: Is the parity clause dead now?

Spencer: I think so. There's this idea that's been named 'parity clause', but there is no clause. We've come out and been very transparent in the last four or five months about exactly what we want.

If there's a developer who's building a game and they just can't get the game done for both platforms - cool. We'll take a staggered release. We've done it before, and we work with them on that. If another platform does a deal with you as a developer to build an exclusive version of your game for them, and you can't ship on my platform for a year, when the game comes out in a year let's just work together to make it special in some way. People complained about that, but you did a deal with somebody else and you got paid for it and I'm happy - we do those same deals, so I'm not knocking you. It's going to be better for you, actually, because people don't want last year's game, they want something special and new.