I can weigh in on this, derailing though it is. My game was rejected for containing nudity based on the design in the gif. I asked about what that meant for my game and what I was told is "nudity" doesn't mean explicit nudity, includes games that would be considered as having a hard-M rating so to speak, and that such games are treated as adult-only. I considered the design unfinished anyways so I resubmitted with what's in those pngs while erasing the heroine's body completely when partially visible to prevent ambiguity, and it was still rejected without even a note.
Considering Doll's Nest came out just recently featuring clothes that don't function as clothing, and a bare doll-jointed design, and wasn't categorized as containing nudity, the sense I get is Valve wants games to define themselves clearly within the bounds of their own vaguely defined content categories, and in-development games from random indies that don't have a cut-and-dry context are treated more harshly because they aren't worth the time to police. It also seems like Valve is very against reconsidering once they've decided something about your game, because that creates internal friction around the weaknesses in such a vague policy.
>>1301480
Anyways Alpha Centauri is some serious bang for your buck and won't have performance issues on a flashdrive. Be sure to get the widescreen/UI mod and check out custom factions.