Do you mind shouting out the other two games that are in your top 3? I love games like this.
I'm mostly a console gamer, so I am not sure if you'd find them on steam or where, but the other two games I play are Hidden Through Time (though the first one is better than the second because the second one they added crappy trophy / achievements to that made the online community clutter the custom-made maps with just a single object on the screen for easy milking), and the Hidden Cats In series, with Tokyo being my favorite for the amount of content in it.