It's of historical interest because Thompson and Dennis Ritchie invented UNIX to port it to an unused DEC PDP-7. In that sense, it may be the most influential video game ever developed. You're most likely reading this page because of it.
Space Travel provides examples of:
- In-Universe Game Clock: The planets and moons following their orbits.
- No Plot? No Problem!
- Ragdoll Physics
- Simulation Game
- Top-Down View
- Wide-Open Sandbox: Probably the Ur-Example.