What I love most about 8-bit era games are how small they were storage-wise. Most of the ROMs are tens of kilobytes for the entire game. Developers were severely constrained by the hardware limits which led to some creative decisions, eg. the bushes and clouds in Super Mario Bros are the same sprite just drawn in different colors. All code was written in pure assembly for efficiency and size.

To put it into perspective, AAA games today are one million times bigger.