Strictly speaking, as long as you only have one base thruout the game, that's a One City Game.
As even that looked "too easy" to someone, further restrictions and limitations were invented and added.
If you just want to have fun and challenge yourself, do it just the way you like.
If you instead want to compare how well you can fare in the "
One City Challenge" with respect to the Community, you should follow the additional rules of a specific challenge.
I presume there ONCE was a thread explicitly stating those rules. But... I had missed it in the beginning and never could find it later.
Doing a search for "OCC" doesn't help, as such a search string sould be too short for brilliant vBB...
You can try to search for "One City".
The most informative thread I could scoop up that way is
this one.
.
