The Witness is coming to PlayStation 4 as a timed console exclusive. Given the pedigree of creator Jonathan Blow, you may think that Sony paid out for the exclusivity, but Blows says it was just a matter of the team's resources and preferences.
"People have been speculating that I got a money hat for this agreement with Sony, or that we needed to do this in order to fund development of The Witness," Blow told Kotaku. "Actually, no money was involved at all.
"The real situation is that, because we are a small developer, we only have the ability to launch on a small number of platforms at once. We liked the idea of being on a console, and originally we thought we might be on the PS3 or Xbox 360, but eventually we decided not to target either of those due to the relatively low system specs. After some more time went by, and our release date drifted further into the future, we realized that the next-generation console launch time might be a good time to release the game."
He says the choice came down to the next Microsoft or Sony console. Sony got in touch and provided development kits. He says he doesn't have contact with anyone at Microsoft and he's not privy to their plans, but his technical team preferred the PS4 specs to to the leaked (and unconfirmed) Durango specs. He also said they "like the positioning of the PS4 (it's about games) a lot more than what we perceive Microsoft's positioning is going to be."
Once they were committed to the PS4 port, it was "not practical" to do another console port as well. That made it a "de facto console exclusive" which turned into an official timed exclusive when Blow and his team signed on. None of this means that he couldn't release a PC or iOS version simultaneously, but that will depend on the small team's ability to pull together multiple versions at a time.