Yeah the battle system is definitely a mess. Damage and lust are the same bar, but that's only really alluded to in one of the skippable Sen questions during the intro so it wasn't exactly clearly explained. Then I decided give them different tooltip descriptions as if they were separate damage types, hadn't considered that could lead to confusion.
I'm considering future improvements to the battles, and was thinking of making the 'pain' damage a delayed increase to lust. Like it adds a status to the opponent that waits until the end of their turn to apply any of the lust? And I could also add some sort of 'reeling' debuff if you take a bunch of pain in one turn to encourage big combos. But that might be adding too many layers to an already complex system.
The enemy AI is something I'm proud of, and I'm very glad to see it enforces the feeling of desperation. With full focus, Max is completely offensive, using charged every few turns and trying to wear you down. Once he loses the first stack of focus, he'll start playing defensively, dedicating turns to stability if it's broken, attacking if it isn't. Minimum focus he just uses random tease actions, won't even try to pin you unless you're already against the wall.
Text length is certainly an issue. It's a world I've been developing privately for a few years, and I kept feeling the need to incorporate X lore bit in there. I care a lot about the 'context' in my smut, and all that fluff does serve to enforce that, but it's definitely unnecessary outside of my own brain fuzzies. (I more than doubled the length of the loss scene after editing it -_-)
For the art. My plan for that would be the photos that were described in the win loss scenes. Each fighter would have a character photo with just them used as an introduction for the character, and match photos for each win/loss scene (The photos looking like polaroids). I did try to make the character photo for Shade, but my amateur pixel art couldn't handle the pose I wanted for it. I ultimately gave up and just wrote the match photos into the final scene. But a future expansion would attempt to capture that idea with actual art.