descentchampions.org

http://www.nesworld.com/n64-unr-ultradescent.php

Descent was supposed to be on the N64???

Whats this about?

Well it was on Playstation, and eventually had redesigned levels in Descent Maximum, so it wasn't unrealistic.

Matt/Mike would probably be able to confirm. It sounds like it was planned but eventually canceled, and I would suspect the cause was that a) it didn't fit into their plans with the company split, Freespace and Descent 3 on the way, and b) an N64 port wasn't expected to be successful enough to justify putting those plans on hold.