Replying months later …
Nobody ever seems to mention this but there is a whole other game buried in The Witness. It has to do with wandering around finding patterns in the landscape, allowing you to activate the black hexagonal pillars scattered around, and getting through doors that you seemingly can’t open into new areas. Spent weeks chasing it all down, but can’t finish the game though. Defeated by Grieg.
Also good for spending weeks on,
You are the last servant of the king of the underground. He is asleep and you have to wait 1000 days for him to wake. Game proceeds in real time. Sort of. Includes a complete copy of Moby Dick,
You are a painter exploring an island and painting pictures. The game has a huge range of scenery to paint and areas to explore.
Give rides to departed souls who aren’t ready to pass on.
Dragon Quest Builders 2
You can spend months on this once you finish the tutorial, which seems to go on for the entire game and take about a month all by itself.