Back then, I spent a lot of time generating amazing landscapes with the free version of Terragen. One of these image served as my desktop background for several years.
And the pure assembly demo's showing realtime Mars like landscapes, my brother was always looking for precomputed tables to avoid the expensive div and mul, fun times. Software was optimized in size and execution speed in the early days. Also remember the first voxel based flight simulation like Novalogic's Comanche.
https://en.wikipedia.org/wiki/Terragen