Wiki article on the PDP-10, with pictures:
https://en.wikipedia.org/wiki/PDP-10
They were still using one at South Bank Poly when I briefly worked there in the mid 80s.
I suspect you were playing Lunar Lander on a PDP-8. They were quite popular in college computer science departments in the 70s, and some soldiered on well into the 80s.
https://en.wikipedia.org/wiki/PDP-8