Before GOG, I had only played "Return of the Incredible Machine: Contraptions", since I had received it as a gift from my parents when I was 11.
I quickly become addicted to it. The game had a great balance between thinking and humor.
I'll be the first to admit that these games are definitely targeted to kids. That being said, some of the puzzles are still very challenging, especially in the later levels.
If you like games like "Crazy Machine" or "World of Goo", you owe it to yourself to see the parent of those games.