Dark Spelunker is a SFCave clone. A similar game entitled UrthWurm exists for PC (DOS version). It’s a simple game where you guide a worm with one key, changing its direction toward up by holding the action key, while gravity pulls the worm down when you don’t hold the action key. Interesting graphics (but very small amount of it), save high score feature, no sound or music, and not so good gameplay.
I can only compare this game to UrthWurm and it is much inferior to it. No level-based gameplay, no changing graphics, no surprise features, and poorly tested gameplay. To me in Dark Spelunker the action key acceleration is too low, while the gravity too high. This makes the game too challenging too early.