Sure it was pre-rendered, but it was still impressive to see PCs do that at the time because of the sheer amount of storage it took. Myst basically required a CD-ROM drive because the game is basically made of pictures, PCM audio and video. There's an astonishing amount of video in that game from the early 90's. It was another symptom of CDs having an astonishing amount of capacity for their era. Myst couldn't exist on floppy disk.

It is pretty cool to see what they've recently done to Riven. They really brought it to life in Unreal Engine.