I suppose you could call games like this proto-clickers. The main difference from clickers being that there's some actual gameplay here, not just an endless chain of upgrades.

You buy some fish, feed them and they shit money. Then you buy the fish that eat those fish and shit diamonds, and so on. Every level some new mechanic or tool gets introduced to keep things fresh. You have to fight off aliens that eat your fish, you get a battling fish that attacks aliens, etc. Before long, things get so chaotic that you end up clicking all over the screen rapidly, constantly buying new fish, feeding the existing ones and catching their droppings. You do get a snail that helps you with the latter, but, I mean, it's a snail, what do you expect from it?

I now kinda understand why people get aquariums. There is some sick pleasure in being in charge of lives of stupid animals and protecting them from aliens. But it is also very tiring. I can't play this game for longer than 20 minutes at a time.

The coolest feature here is that they let you create your own screensaver. Unfortunately, I haven't used screensavers since like 2004, and am now running this on Linux, so this feature just doesn't work here. I wonder if it does on Windows 11.

I think a game like this was much more valuable in the pre-internet era (which for me was pre-2007) because, for all you knew, it was one of a kind. But after you've played two or three of these, you start seeing the seams.