You didn't play Myst Online: Uru Live back in the day? Don't feel guilty, not a lot of people did. But if you hated yourself for missing out, the game is now back online; free to play and soon to be open source. The game will cost nothing to download and play, with only one server open, and the developers are accepting PayPal-donations to keep themselves up and running.
If you want to check Myst Online out, head over to the official website to sign up and download the client. I'll be the guy in corner, utterly confused.