EDIT: CAVERUN.MID HAS BEEN FOUND!! Thank you to @drmelon, @twilight-sparkle, @mintexists, and @CHz -- check the comments for more info!
Alright, Cohost, I need your help for this one.
In the year 2000, British software house The Game Creators published their own game creation programming language based off BASIC, titled DarkBASIC. This was the first programming language I ever got my hands on as a child, and by and large it was completely incomprehensible to me. My proudest achievement was making it so that when you pressed the spacebar, a sphere would flash different colors.
HOWEVER
DarkBASIC also came with a few demo projects to show how to use the engine: 3d rendering, input, audio, and the like. One of these projects was called Cave Runner.

By and large, it was a pretty basic tech demo, with a game added on top: you could strafe left or right while running through this 3d cave, and if you ran into a wall, it would start the game over again. However, this game was intoxicating to me as a however-old-I-was kid. One of my favorite things to do was change random numbers in the source code to see what would shift: one time, I made everything twice as fast, while another, I made it so the arrow keys rotated the character instead of strafing. It had a big effect on me as a kid! The real star of the show, though, was
THE MUSIC.
Cave Runner had a single song, titled caverun.mid. I can barely remember what it sounded like, but I know it was a fantastic track, making full use of the crunchy bass midi sound of the era. There's a chance it was just mid(i), but I've been beset by the deep craving to hear it once more.
Unfortunately, it is NOWHERE to be found. I've spent the past hour digging through every uploaded iso of DarkBasic on archive.org and not one of them has caverun.mid (or even the Cave Runner demo project!) with it. The ONLY record of the demo on the internet are the two screenshots posted above: one of the source code (which doesn't have the requisite files) and that single grainy screenshot from a review blog. No videos, no documentation, nothing.
So I turn to y'all for help. Do you remember Cave Runner? Do you have an old copy of DarkBASIC? Do you have any idea where I could find this one-off song from a tech demo of a defunct programming language? I cannot rest until I hear it again.
Intrigued by this search - never heard of DarkBASIC, and also never heard of a language based off Basic that had a built-in 3D renderer??
Edit: quick google shows it was a game engine that used DX and a Basic-like programming language. Super neat!