This is the readme description from Aminet:
and a screenshot:Short: Collect gems in 3D cave! AGA/020 (fixed)
Author: szulat@pozn4v.put.poznan.pl (Szymon Ulatowski)
Uploader: szulat@pozn4v.put.poznan.pl (Szymon Ulatowski)
Type: game/demo
This is the demo version of a new 3D game. The rules of the game are like in
old good Boulder Dash 10 years ago: collect diamonds and find the exit. You
will have to face brand new obstacles in the 3D version and the game gives
new features: view from the player's position, flying, bombs. The program
contains review of the characters appearing in the game and a recorded
example of a contest. You can try your skills just on one level in this
version. More levels and other attractions will be available in the full,
comercial version.
See also 'Speed!.lha' in aminet:game/demo

I've just been browsing on Google and came across another 3D version of boulderdash from First Star see: http://www.firststarsoftware.com/GuardianQuest2003.htm See also: http://www.firststarsoftware.com/boulderdash.htm