> "Why should I bother with lots of ammunition? I use it, and rebuy it at the front!" - it changes a lot, it's risky and I don't like it.

Man, you must have *hated* tents :)

Note a chemical plant will
a) Require quite some time to be built. I would suggest build times to be quite a lot longer than normal, in exchange for not requiring a Clonk to babysit it
b) Only allow you to buy stuff in your own base region. Sou you must bring (and install!) a flag, which is a huge risk, as an enemy might just take it away

> A burning castle should burn!

Yes, fair point. That has absolutely nothing to do with buying, though - it's about how fire and repairing works. My proposal would be to not have instant extinguish - it's not realistic to extinguish a whole building with just a water barrel. Instead this should just make the building extinguish faster. Also repairing should obviously take some time. Tricky to work out the details, though. I'll think about a design.