Discovered Fisher-Diver on your birfday! Happies for you, and me too!
The game dynamic is neef. Unlimited Depth is fun, but Limited Oxygen does put a limiter on that.
A lot of the fun for me is encountering the really large creatures. I’d play this game for much longer than the diaries last, and Limited Storage doesn’t allow for that much Really Large Creature discovering.
After the week or so of diaries, the player more or less has bought all the items. But there certainly is a lot of playability left in what you’ve designed. With more items, there would seem like more of a point to coming back with a couple thousand dollars. Playing with the Really Big Creatures is enjoyable in and of itself, but coming back up tends to be a reminder that there’s not much to do anymore. Other weapons, perhaps? Maybe a net. Towing several of the critters around at once seems like it could be fun. A breeding area? A Really Big Creature beacon? (crunch crunch when they meet up at it)
You’ve come up with a very unique game that leaves us wanting more. You certainly have something here.