Exactly right! I had been working on a prototype for a Doom-style game in the summer of 1994 for the 3DO and built out the beginnings of the “sort polygons AOT” concept. While the idea was conceptually simple, the details were a bear. I guessed that using keyframes with the entire polygon list plus deltas would “just work out” and fit in the limited storage and computational budget of the PS1… and I was very relived when it was clear my intuition was right. (Otherwise we would have needed to redo the entire game engine.)

Another challenge was dealing with foreground objects: you have to somehow sort these into the pre-sorted background polygons. This mostly worked with bucket sorting but we had to use the gross hack of allowing each foreground object to have tunable “push-back” to fix sorting glitches. This required manual work for each level.

Finally, while precomputing the per-frame sort order for a game like Crash would be trivial now, in 1995 we had to build our own Beowulf cluster thingy and farm the level precompute out in pieces to the artists’ SGI workstations, and levels typically took an hour to process. The artists LOVED that. :)