A quick new entry and for another Quicksilva game which was listed in a few adverts as coming soon for the likes of the C64. However there seems to be no evidence of the game anywhere.
Pretty much straight away we found out that the game was eventually released as part of a 30 game compilation that was released by Argus Press.
Additionally thanks to John Christian Lonningdal, we find that 3D Tunnel was released by New Generation Software (Possibly distributed by Quicksilva). Backups will be made for various preservation websites soon.
The game itself can be grabbed from here, so its case closed!
Contributions: Anon., John Christian Lonningdal