[cableshaft]

So the guy who made the classic Prince of Persia kept a regular journal during it and his previous game, Karateka. You can buy the journals on Amazon[1].

I found out that this year Digital Eclipse decided to turn those Karateka journals into an interactive documentary, and that's now on Steam under the title 'The Making of Karateka'[2].

[1] https://www.amazon.com/Making-Karateka-Jordan-Mechner-ebook/...

[2] https://www.digitaleclipse.com/games/karateka

Also a lot of Valve games have audio developer commentary that can play while playing several of their games[3].

[3] https://developer.valvesoftware.com/wiki/Commentary_System

Also Zachtronics (SpaceChem, Infinifactory, Opus Magnum, Shenzhen I/O) released a book called Zach-Like[4] which had a lot of design documents from their various games. It's available in a physical format as well as Itch and you can download it on Steam also. I have the physical copy. It's just a PDF though. Still super interesting.

[4] https://www.zachtronics.com/zach-like/