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
Lately, we have someone in the office playtesting The Witness. He had never seen the game before, but he was really good at figuring out how
— Jonathan Blow (@Jonathan_Blow) June 11, 2015
to solve things; a lot faster than average, I think. Today he finished the game, after 8 full-time days of playing. So, that is about
— Jonathan Blow (@Jonathan_Blow) June 11, 2015
64 hours of gameplay. He didn't quite 100% the game, but he is at maybe 97%.
— Jonathan Blow (@Jonathan_Blow) June 11, 2015
So I would expect the average time of 100%ing the game to be over 70 hours. This is in a game with no repetition or filler ... everything
— Jonathan Blow (@Jonathan_Blow) June 11, 2015
you solve is different and has its own reason for being there.
— Jonathan Blow (@Jonathan_Blow) June 11, 2015
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.
(If you are not a completionist, you can get to the end in much less time; it's just that there's tons of optional stuff.)
— Jonathan Blow (@Jonathan_Blow) June 11, 2015
A significant step up from Braid, then - even accounting for time spent stuck on puzzles. No wonder it's cost Blow so much.
[Doing the math, this means The Witness has 14 times as much stuff to do as Braid did.]
— Jonathan Blow (@Jonathan_Blow) June 11, 2015
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.