Indie developers wishing to release titles for Xbox One via the [email protected] program must not launch the game first on PS4 unless an exclusivity agreement has already been put in place with Sony, Ridiculous Fishing developer Vlambeer has told Joystiq.

"Microsoft was doing reach-out to certain developers back in the early days of [email protected], and we discussed potentially bringing Nuclear Throne to Xbox One with them," Vlambeer co-founder Rami Ismail explained.

"There had been mentions beforehand that there was a launch parity clause in the contract, with the exception of games that were already signed to another platform during the announcement of their self-publishing program. Thus, before we signed with Microsoft, we e-mailed Sony that we quickly wanted to sign Nuclear Throne with them with a month of exclusivity."

Any kind of exclusivity agreement doesn't come down to platform favouritism, but a means to focus efforts on one version at a time.

"Honestly, we've had enough trouble with our promise for a simultaneous release for Luftrausers, so by getting rid of parity we'd be able to focus on one platform for Nuclear Throne first. We also liked that we got to honour our long and super-pleasant cooperation with the people at Sony that way."

Whilst Microsoft isn't demanding exclusivity on [email protected] titles, Ismail says his team would "rather Microsoft allow us not only the freedom to self-publish, but also to publish in whatever order we prefer .... We'll keep pushing for Microsoft to drop the clause, and we'd recommend any other developer to do the same".

Ismail added: "To be honest, we're in the [email protected] program mostly because we think Chris Charla [director of [email protected]] is a person that genuinely cares about games and because we feel that with our visibility, it might be a good idea to go through the gauntlet and report back on whether it's a risky or unpleasant experience."

Despite Ismail's concerns over release parity, he believes [email protected] is a great program.

"So far, there's nothing but good news when it comes to the program - Microsoft seems to have taken the cue from Sony and joined the platforms that allow for self-publishing," he said. "Especially considering that this is still sort a pilot program, they're doing great. More platforms allowing for self-publishing is good news for everyone that makes games, and in the end, that's the part we really care about."

Yesterday, Microsoft announced a list of 33 studios already working on games for [email protected].

Source: Joystiq