One of the key points of fulgora is no free water. I found a ruin that made water, negating a huge part of the balance here. Can you remove that or make it optional?

Yes, I noticed this myself. I try to add space-age as an optional (?space-age) dependency and add Fulgora as an excluded surface. So far I don't know the name of the surface internally (which a planet/moon/control room is).

clear_area() is the function that needs the support added. It currently excludes only tiles with type="resource" (see parameter invert = true).

Practically the same goes for Vulcanus.
Surface names are:
fulgora
vulcanus

1.2.6 has included a workaround which excluded these planets for now. If you know how to fix it, you can send me a PR at github: https://github.com/Quix0r/AbandonedRuins20

mooklepticon was complaining about some ruins spawning water tiles which is a problem on planets that aren't supposed to contain any water.
He wasn't talking about about ruins spawning on oil and lava.

Yes, I have mixed that both. I still see it as an issue that ruins exist on "seas".

1.2.8 has removed the static planet names and switched to a more flexible approach. Still ruins with water might spawn on Fulgora (known missing checking).