TL;DR: [GitHub project] with PDF schematic, datasheet, and KiCad schematic.

I was inspired by Ken Shirriff's 2016 Hackaday Superconference talk [video] [Hackaday write-up] to try to reverse engineer a chip from its die photo. Ken recommended going to Zeptobars, downloading a die image, and diving right in, so I did.

I chose a digital chip that wasn't too complicated, and a BCD-to-7 segment decoder seemed ideal, and the [datasheet] already gives the pinout and function, so I wouldn't have to start from zero.

To give you an idea of what it was like when I started, here's a low-resolution image of the die (high resolution at the above Zeptobars link):