Concepts & Originality
Moodboard looks ok.
Flavortext is nice. Alien ecosystems are cool.
Rules Clarity
Some superfluous rules. Not to bad.
The rule seems a bit complex. There are three types of special terrain, and they all have their own rules, there's some random effects some of them chain into other effects.
Adherence to Theme
Things only grow conditionally, either on a 6+ on a D6 or if a player includes blast/indirect weapons in their army. Not sure how reliable that is.
Alien ecosystem growing in explosive spurts is very on theme though.