I realize this is an old thread, but am posting in the hope that I may revive it...Lately found that I missed Myth, and in the process of looking for a replacement, I discovered that the original Myth has been lovingly kept alive and kicking by a group of very dedicated developers working for free. There's even a game server. (more info here:
Project Magma: What is Myth?)
So I loaded it onto my MacBook running Leopard, and it runs beautifully. Now I'd love to find some people my age to come play! If you're up for it, send me a message.