You got a lot of "horror of the deep" vibes without a lot of horror of the deep. This game is missing monsters. The salvor has to constantly having to be stealthing around to avoid getting raped by fishmen, zombies, mindflayers, octopi, giant fish, whatever. Maybe have a ticking clock element where the longer you're there, the more bad things come out.
I feel like the tiddy and ass expansion are wasted here. Throw in some monsters with variable scenes depending on what her size is. Hell, I think you should throw in hostile Salvors that will capture her if you don't play smart. Then you gotta ransom to get her back, maybe get some scenes if you take too long.
Something, brother. Conceptually, this game is dope. But you gotta put more into it. If it's just "Ah, but look look! Her tiddies are big. Isn't that inconveniant and sexy?" then it just ain't worth a play. But it could be. Hear me out on them ideas. Look forward to seeing what this shapes out to be.