[RealDinosaur]

Braid and Witness could have been written in Unity though.

I'd argue that dealing with high level concepts such as game/level design and art direction and low level stuff like graphics and rendering simultaneously is insane. I don't know how Jon Blow did it, but personally being able to abstract away all that low level stuff makes the design process way easier for me.

There was a recent game, 'Return of the Obra Dinn', which went the opposite way. It was the dev's first game with Unity, and he attributed most of his success to the Engine.

It doesn't look like a Unity game, it doesn't play like a Unity game, and it has won several game of the year awards.

[loup-vaillant]

Come to think of it, there's Antichamber, a non Euclidean labyrinth based on Unreal Engine (4, I believe).

As for how Jon Blow did it, I suspect having his own engine let him explore gameplay ideas more readily than using a generic one. The time travelling in Braid and all its variations would be pretty hard to bolt on a generic engine: it's not just rewind, it's partial rewind, with some entities being immune to the rewind. There's even a level where time goes forward and backward depending on the position of the main character. Go right, forward. Go left, backwards.

For The Witness, it's a bit more subtle, but about a third of the game required pretty crazy 2D projective analysis of the 3D world (the "environmental puzzles", don't look them up if you don't want spoilers). While it didn't en up being central to the game, it was basically the starting point.

The engines of Jonathan Blow's games are more central to their gameplay than for most games. Still bloody impressive, but probably less unnecessary than one might originally think. Also, Jonathan Blow has pretty strong opinions about game development, and I got the feeling that he disagrees with most generic engines out there. Working with them would probably caused suffering, whose cost he didn't want to pay. (Speaking for myself, my productivity drops pretty sharply when I spot stuff I too strongly disagree with, and I can't fix it.)

[wtetzner]

Maybe Braid and The Witness could have been written in Unity, but it's not at all clear that it would have saved any time, or that it would have resulted in something as good.

There are a lot of issues I've seen devs run into with using Unity, sometimes much earlier on than you'd expect. Unity was designed to be a generic engine, which means it won't be ideal for every use case.