The Witness will probably take you 70 hours to completely finish
The Witness is going to offer absolutely loads of content for those interested in a completionist run.
The Witness is Braid developer Jonathan Blow's second major release, and unlike its precursor you won't be able to knock it over in a few hours if you're good at puzzles.
According to Blow's experiences with internal testing, unlocking every secret the game
Although testers are often very skilled players, gamers in the wild inevitably exceed developer expectations, so you can probably expect hardcore players to knock this figure down considerably.
For those of us with busy schedules, Blow said it will be possible to finish the game without seeing and doing everything, so you're not necessarily signing your life away if you elect to give it a go.
A significant step up from Braid, then - even accounting for time spent stuck on puzzles. No wonder it's cost Blow so much.
The Witness is a PC and PS4 exclusive expected to release this year. Maybe we'll get a release date at Sony's E3 2015 conference.