If it weren't for the fact that I absolutely loved the comic book, artwork and would dream about winning the treasure prizes, I'd definitely add Fireworld to the list.
I just couldn't stand the Fireworld game itself. There were challenges at every room, not just some of them, no real useful items, unlike Earthworld, and no matter how many hours I played, I never got a single "clue screen". (Never got more than 2 in Earthworld either)
The game got it all wrong in my opinion, but the rest was pretty cool.