I skimmed other posts, but did not see these mentioned. Apologies if these have been addressed already.
1) page 9, under PEOPLE, paragraph 4: "...the civilization that ruled the region up until a millennia ago." --- 'millennia' is plural. Since you seem to mean just one, you want the singular "millennium".
2) page 18, under SHADOW AND ALIGNMENT, first sentence: "The underlying theme of Ruins of Symbaroum is the struggle between nature and civilization, between creativity and discipline — and what happens when ??? (humanity mainly) cultivates nature;" --- The parenthetical needs a referent, probably a word or two in the position marked with "???". Perhaps "a civilization" ?