Sandbox battles

Several older RTS games have maps/modes where one person defends and others attack.

Are you allowed to repair/upgrade your fort after the "peace time"?

Perhaps it would be easier if there was one group of defenders and another group of attackers.
And then they would have different "disabled units" to enforce their role.

I'm also interesting in trying something like that, but the rules have to be somewhat complete first.

Yes, it's not fun unless two players are good sport. That is why I doubt it's a good field for a competitive match, unless there is an option to disable shields!

Come to think of it, that sort of gameplay naturally happens in FFAs.

Sometimes, players in FFA don't engage any of their neighbors because starting a fight you don't instantly win is just asking to be invaded by another neighbor while your forces are depleted.

I don't know that any FFA went as far as 30 minutes without any aggression, but if you look at long FFAs, you'll see what kind of gameplay you'd get. It's not very interesting.

For FFAs specifically, it means as soon as someone is identified as a target, they get instantly crushed by an overwhelming force of the combined value of all the other participants. That's what it would feel like to be on the receiving end of a no fight for 30 minutes match. Whoever is best at macro will have such a commanding lead, the other would get immediately destroyed.

Hey man if you can find other players willing to try it, go ahead. I think that's a pahse thing. You'll try it, it might even be fun for a bit, one of the players will discover how powerful the silo really is and all the other players will feel like that ruined the mode and will want to start banning super weapons too.

We went down that road multiple times in the past and some players still long for it. Talk to GrandorCZ. As far as I know, what you describe is exactly his favorite thing.