Explore caverns searching for crystals and grabbing fuel to stay alive, while you avoid vicious, fireball-spitting creatures.
Use the arrow keys to move your ship.
Collect crystals to earn points.
The game will end when you run out of fuel, or if you are struck by a fireball.
To mute / unmute the sounds and music, press M.
Protip: Higher value crystals are generally found deeper in the caverns, so if you're trying to find the elusive 1600-point yellow crystals head downward any time you can.
For version 1.4 I've tweaked the controls for the player's ship (I agree that the controls haven't settled down to a point where they feel right yet, but hopefully this tweak will get them a bit closer).