[ChickeNES]

This is still one of my favorites: https://ultra64.ca/files/other/Game-Developer-Magazine/GDM_S... detailing how Resident Evil 2 N64 was able to fit in a 64MB cart despite the PSX version needing two CDs.

[somedude895]

Modern Vintage Gamer has a great video on that as well: https://youtu.be/BaX5YUZ5FLk