In the latest blog post for The Witness, Blow revealed that a physical version is extremely likely at this point, but you’ll have to wait until after the game launches digitally:
We’ve had some people asking us whether there will be a physical retail release of The Witness. It’s seeming likely, as we have been in talks with a couple of parties for a while about that possibility. *However*, it looks like if there is a retail release, it won’t happen until a little bit after the digital release. The reason is just that we need all the time we can get up until the release date in order to get all the finishing touches into the game; but because of the lead-time involved in physical manufacturing and distribution, we would have to freeze the game right about now in order to have it on store shelves for the release date. *Or* we could delay the digital release date in order to wait for the physical. But I don’t see a good reason to do either of those things. I would rather just focus our energy on making the game as good as we can make it, and a retail version can lag behind by a little bit.
Developer Thekla will be doing a little more voice work in early January (expect cast announcement in 2016) and, right now, they’re “doing *lots* of little gameplay fixes all around the island, like, what does collision feel like in this area when you bump into things, what happens if you are standing in this doorway and the door tries to close on top of you, all that kind of thing.”
Visuals, meanwhile, “are mostly locked down at the moment.” At this point, Thekla is mostly making “making spot-fixes here and there every time we see something we don’t totally like.”
[Source: The Witness]