The Halley Project: A Mission in Our Solar System

In The Halley Project, the player is a star pilot who is given missions to
travel between various objects within the solar system. The player starts out
from a base on Halley’s Comet and must first make his way to Earth, and then
back to the comet. As the missions are completed, the player’s rank increases.
After completing all missions, a code is provided which could be mailed back
to the software publisher, who would send back a letter with instructions to
access a secret mission.