Well, two in fact. One of them isn’t nearly very good (Noah’s Ark), but the other one, well… I haven’t slept since I’ve found it (okay, I didn’t find it until 10:00 am, and I’m at work, but that doesn’t mean it wouldn’t keep me up all night).
Insaniquarium. What a great game! It’s not extremely hard, and it doesn’t scale up to the point where you need Jedi reflexes and to control your cursor with your brain, but it’s still a sweet game.
Check it out.