When using a user-created map, the computer uses the standard size as the basis for the rules it uses. Or at least that is the situation that appears to be happening. How can you set it to rules that apply more to the size of the map that is actually being played? (i.e. 256x256 using the huge rules)

For example, marla's gigantic world map uses the standard size rules instead of the huge rules even though it is 256x256.

This throws the games way off. Having the amount of cities of the supersize map, but only having to get the lowered amount of tech costs, etc. Getting to the modern era in 1200 AD. Pretty much a problem.

I could try changing the standard size in the 'World Sizes' in the editor, but that seems like overkill.

Based upon the answer I got to a nearly identical question asked yesterday, changing the World Size entry numbers is exactly what you need to do. If you play with the normal game rules, just "edit rules" on that map to do it. If you play a mod or some other set of rules, copy the .bix for the rules you use, change the world sizes how you want them, and import the map.

Look at the scale used for the 5 normal sizes (60 X 60, 80 X 80, 100 X 100, 130 X 130, and 160 X 160), and then compute the appropriate numbers for 256 X 256 and put them in the editor.

Playing a normal Huge game last night, I hit Industrial Era by like 1200 AD or so. :)