Thanks for the feedback, and glad you're enjoying the game so far (or at least some of it.) "BDSM" is kind of a nebulous thing. In terms of powerplay, that's already obviously in the game. Bondage as well, though only lightly, as is a VERY light bit of pain with slapping and such. In general I tend to not think in terms of "BDSM" or any specific kink (besides mind-fuckery of course), but just what make sense and presents itself as the narrative unfolds. There will be more art as time goes on: art is the most costly part of the process in terms of time and effort. This game took 13 months to make, and a good third of that (at least!) was just art creations. On the other suggestions:
1. Most of the scenes are designed so that you'll only really see them once. The notable exception is the end fight, but unfortunately there's not a good way for me to put a detection counter there because it doesn't loop. Losing is a game over, so there's no way to add the information that you've already lost once to the save file to trigger a "skip scene?" prompt. In theory I could monkey around with a separate file to save this information, but that has downsides too (wouldn't be able to tell two different playthroughs apart for example).
2. Ha, glad you noticed. Just kind of the way it turned out. I try various things as I'm designing characters and end up going with what works. I just wasn't happy with more animal-esque junk on the enemies, or more human stuff on Mezz. It's a little inconsistent, but not the end of the world.
3. I experimented with some various sounds, and in fact GT DOES have more sounds than CS1 did (especially proud of the slaps). Ultimately I just wasn't happy with the way more obviously explicit sounds felt. Ended up taking you out of the experience. I'm also mindful that some people might be playing this in less than entirely private situations, and given that I've been there myself, I know I appreciate a game that, should the headphone plug get yanked, won't immediately blanket the entire apartment with the sounds of an orgy. By sound alone, Cruel Serenade sounds (mostly) like a perfectly ordinary game, and that's intentional.
4. Like I said, some new content coming eventually. Probably not a lot in terms of extra battle content or new enemies though. Might have a little additional stuff there in the last pack.