A very uniquely styled game.
At its core, this is a casual treasure hunting game. You click on the map, the unit you control moves, if you find some treasure, you grab it, if there's a curio you explore it. That's it. Sounds pretty simple, primitive even, and that's because it is. Nevertheless, the game manages to pull it off because of the unique immersive aesthetics. You play as one-man HQ for your diver operator. The graphics is black and white with some chromatic aberrations to simulate the CRT screens you're supposedly looking at. The sound design is exceptional, all the sounds you'd expect in a deep ocean wreck are there, the creaks, groans of metal, the drips and splashes, it's really immersive. There's a bunch of fairly simple resource management mechanics, related to things like lock-picking or modifying salvor's body size to squeeze into narrow passages. Nothing actually complex or stressful like managing oxygen supply, or getting killed, it's a very casual game in that regard.
When it comes to story, this is also a fairly simple game, which is fine. Not every game needs to have some epic adventure or nerve-wracking intrigue. Sometimes it's just a dude and a girl teaming up and looting shipwrecks to pay the bills in a CRT-punk, while the game's erotic content definitely caters to voyeur and transformation fetishes pretty organically. I could see an argument that is has hints of NTR, but it's really not "true" NTR, because you do not have a prior relationship with the girl, nor do avoidable (both mechanically and with an options toggle) sexual encounters drive the girl away from you, should you pursue her (you can romance the shopkeeper instead.)
I would've given Salvor Deep 5 stars, if not for one key deficiency. Remember the sound design? Well... There's a catch. The quality of sound design doesn't truly extend to the sex scenes. When it comes to sex, it's very basic, and in my opinion it's a huge case of wasted potential. I get it, VA work costs money, but with just a 10-minute source track of lustful moans and wimpers Salvor Deep could've been an experience truly unmatched by any porn game in existence.
If this game ever gets a better lewd sound track, it's gonna be a true masterpiece, but for now, it's just a good game.