This is a shortish game with the almost unique trick of placing a lot of gameplay in darkness in a cave. The only similar game I can think of is Hunter in Darkness or parts of So Far.
You are searching for a magical crystal in an underground cavern. The rest of the story is mainly atmosphere, and it works well. This game was nominated for an XYZZY for best writing, and deserves it.
Overall, a short, simple game, with at least 3 endings depending on your final actions.
Recommended for its fun-to-length ratio.