When conventional search engines fail me, I often find that word of mouth, so to speak, works just as well.

Does anyone know of a decent sourceport that flashes up Terminal Reality's contender with the Descent series?

Ah, well. That explains a lot. Still, I might re-purchase the downloadable version from 3DRealms. I lost my CD version a long time ago/in a move/someone took it and never returned it.

Long bump, but keep an eye on "Terminal Recall". It's a new engine that can use TV and Fury3 assets.

Imho, Descent 1/2 are nothing like TV or Fury3 except for the 6dof element.

Descent's levels are closed, confined tunnels, and the game plays a bit more like an FPS except with slower turning and Zero-Gravity. Terminal Velocity has wide open terrain, and you control more like an aircraft. You also cannot be stationary, always requiring the smallest amount of forward movement.

EDIT: Since I can post links now: https://github.com/jtrfp/terminal-recall

I found the controls to be quite similar, it was easy going from one to the other.

Updated my last post with a link to the Terminal Recall engine. It's not complete, so you'll need to compile your own copy with JDK and Apache Maven.