This caught my interest immediately and held it tight. The look, feel, and style of it all were coherent and cool. Getting that presentation right is so important for first impressions. For the most part it always answered my wishes, too; right as I was hoping to see levels that don't funnel you into a single designated path so readily I got them and the pacing was tight enough to where dying in a level kept you close enough to where you left off that it wasn't frustrating to try again. If anything felt underbaked it was the story. Your setup has plenty of classic charm - a hardboiled detective, an intriguing dame, a colorful villain group and a charismatic villain - but it feels like we only got the bare minimum from them.
Sweet Pea is a bit dull because she had such a one track mind. Her motive - save the girl - was so basic, and she was -so- singularly focused on it that she didn't show any curiosity toward the people she met or the situation. You wouldn't know that she's a detective by the way she acts. Though it was kind of cute how she tried to make action movie one-liners but couldn't really think of anything other than variants of "uh, I'm gonna kill you now", it would have been more interesting for her to engage with the villains more. I ended up agreeing with how the bad guys saw her; Cotton was right that she was just someone who got taken in by a pretty face and Stonecrop was right that she came off as a kid, someone just barely in their 20s, who hasn't lived long enough to have anything meaningful to say about subjects like life and death. Hardboiled detectives are usually past their prime because connecting their tortured past to the present is more interesting, especially in a story with these themes, than throwing a kid who barely knows anything into a situation where they don't take the opportunity to grow a bit.
By contrast the villains very apparently had a richly detailed history (and I am glad that we only got a taste of that, some things work better that way) that made their actions compelling, but I would have liked to see more come of their plots, grudges, regrets and interactions with each other. This is also where I think you could have done a better job connecting the lewd elements of the story to the rest of it; there are some hints that sex revitalizes the undead (or something) and that seems like it's going somewhere but then it never truly becomes a plot point. Most of the storylines involving these guys just seem to fizzle, too; the Cotton rivalry just blunty ends with no emotional resolution, Bitterback's seemed very underwritten (if they're both former lovers of Zephyr Lily you would expect some tension between him and Yarrow but they don't interact at all), there were hints of discontent from Stonecrop toward Yarrow that died just as quickly as they were suggested &c. Even when it comes to what they were planning it's all a bit vague and generically nefarious. I was left wanting for a scene that brought it all together. Lots of room to expand on the bare minimum.
Most of the time I knew what I needed to do even if I didn't immediately know how to do it. Stonecrop tripped me up because I immediately figured that I needed to bounce her shots back at her but didn't know that you get infinite bullet time during boss fights. I was trying to dodge by dashing (which kind of felt useless without any i-frames, especially here where the shots homed in on you) and getting frustrated with how tough it was to get the bounce angle. Some were saying that there could have been more of an indication for when she's going to fire, but thought the sound cue, her aim steadying, and the glowing cannon were enough as far as that's concerned. If anything a tip off early on that boss fights have that inexhaustible bullet time was what it needed. Seems like I'm not the only one who stumbled upon that by accident and if you don't know to use that then you'll likely never manage to consistently bounce her shots back. The other moment was the vine at the end of the final boss fight. While shooting the glowing weakpoints is obvious to anyone with gamer intuition it's not immediately obvious that this is how you stop the screen-filling thorn vine. A couple of warm-ups where you have to shoot them to remove an obstacle or something leading up to that might have been good to prime the expectation.
Destroying the field did feel a bit anti-climactic, too. That's a moment where you'd usually bring the mine down on him with TNT or cobble together a flamethrower or something. It just kinda catches on fire for no reason.
Had a lot of fun with this, though, and the couple of spots where gameplay segments were a bit arcane only stood out because it usually struck a balance between letting you know what to do and giving you some room to experiment with getting it done.