Caverns of Mars

Caverns of Mars is a vertically scrolling shooter for Atari 8-bit computers.
In Caverns of Mars, the player descends into cave and at the end must retrace their steps back to the top.
The cavern is divided into different sections depending on the skill level: the easiest setting has three sections, the hardest has six. The final section is
always a reactor which the player lands on and sets to explode. The ship then reverses course and has to fly up and out of the caverns to escape
before the detonation occurs.