How about any dialogue to change the rule setting before starting a scenario?
Except for having the possibility to read the description, rules aren't different from hidden scenario scripts. But most rules are ment and designed to be switched on or off when you feel up to it. Doing so physically changes the files and kills any network compatibility.
Wouldn't it be nice to have any kind of dialogue before starting a scenario where you can select any rules you want without the need to change the files? In the lobby it should be possible to live edit and with visibility for all players.
In addition there are two entries in the scenario.txt needed, like 'IncludedRules' and 'ExcludedRules' to define those rules which should either be switched on or off everytime (e.g. there is no sense in having the option to switch on Construction Material if the scenario doesn't provide it; the developer disables this possibility to protect the player from a trial and error procedure to find out which rules won't work).

From what I've heard this isn't easy because the engine somehow would have to preload the objects. What about this?