Recently, I discovered Bobogram, and I had a blast with it. It’s a rule discovery puzzle, where the premise is the rules are cut off, so you only know how they start. There are some important details that help you discover what the rules are, for example, that puzzles only have one valid answer.
If you enjoy puzzles, I really recommend giving it a go. I wasn’t too sure about it when I started, but the feeling of eureka when everything falls into place is hard to match. I wont spoil anything here, just go play it if you can.