Greyhawk, per Gygax, had (among other things)-
1. A crashed spaceship, complete with laser guns.
2. A pocket plane that put you in Alice in Wonderland.
3. Multiple ways to get to other prime material planes, including but not limited to apocalyptic and western settings.
4. Mechanical devices, robots, and ancient computers.
5. Had villains (in his home game) that included Dr. Who and Colonel Sanders.
6. Created the Odd Alley and Weird Way in the City of Greyhawk (look it up).
I could keep going, but the 70s ... they were different.