> My proposal right now would be: You can use every production building without restrictions everywhere.

I don't mind. Note that my post didn't even mention that anymore - just that structural buildings block enemies. And that you can't buy stuff, because it's not your base.

> or better: When not inside an enemy zone ("neutral" buildings).

Yep, that's exactly how I intended it to be. Neutral buildings may be used by all, as long as it makes sense. Not sure what this means for doors, for example: Should they open by default to anybody, or stay closed? Maybe open just from the inside? I'd hate if we had to implement manual door control just for this...