Carl Sagan was an astrophysicist, science popularizer, author of the novel Contact and, to describe him in the most trendy terms possible, the Bob Ross of astronomy. He presented a number of fine documentaries about science and the universe, most famously Cosmos. He also, it turns out, briefly imagined how you might make a video game based on his work.
"The question is how to design a home video game whcih would teach a great deal of astronomy in a context as exciting as most violent video games," the document begins. He goes on to imagine a game that simulates parts or all of a galaxy, taking place "over such a long period of time that stellar evolutionary events would have to be taken into account," and in which players would solve puzzles that would at the same time teach players the "geography of the Milky Way Galaxy."
Continuing, Sagan writes that "There are two natural starting points -- (1) when we begin on the Earth and have to find something elsewhere in the Milky Way; and (2) when we start outside the Galaxy or at the center of the Galaxy and our job is to find the Earth." He then suggests that the game might function as a tie-in with his novel Contact, which would be published two years later.
The document, which is just a page and a half long, is included as part of the collection of Sagan's papers held by the Library of Congress. You can view both those pages online here. It's unclear whether he ever thought about or pursued the game beyond making these notes, but I thought it an interesting read for this rainy Friday afternoon.