Looks excellent, can't wait to try it! Do have some preliminary questions, though:
1) The description makes this sound like this is an spinoff of a... presumably more SFW project that's on Steam, is that correct? If so, what's the name of that version? I might want to support it as well.
2) Will the game have routes/ending options that keep the girls at more moderate sizes? 500+ kg is a little extreme.