The subject of console parity, has been quite controversial, with several multi platform titles being supposedly held back as certain versions needed to retain a relatively similar level of visual fidelity, so as not to be distinguishably different from the other versions of the same title.
In an interview with EDGE magazine, Phil Spencer was asked if the ‘parity clause’ is dead, to which Spencer responded:
“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.”
While Phil Spencer's response on the subject of the 'parity clause' is somewhat vague, it does reflect a bit on the situation. Whether the apparent parity that does seem to exist in game development today, is due to any individual company's "strong-arm tactics", or if it's solely a developers' choice is not clear. Although, as the console market tends to currently lead the majority of game development, it would seem a logical strategy for publishers to retain a certain level of parity as to ensure stronger sales of the more profitable versions.
A relative balance has to be attained to establish that a certain game engine can perform well enough on the consoles' hardware, therefore several assets have to be reduced in order to maintain a more playable frame-rate. Having the same engine balanced and restricted on multiple platforms, causes the overall visual quality of a title to be dropped considerably, and any further enhancements for a particular hardware, if even possible at that point, could lead to a substantial increase in development costs that could prove quite unprofitable for the developer or publisher.