In Multiverser, players play themselves as characters who, when they die, travel to other universes. Instead of scrapping their characters and starting over, they can continue indefinitely. The game can be anything you want it to be, since the players can end up in the setting of any TV show or movie, any other game setting, one of the worlds in the supplement books, or a world dreamed up by the GM.
Although the book is huge for an RPG rulebook, it's not as intimidating as it looks, and the system itself is fairly straightforward. It's also designed to incorporate every possibility, from magic to psionics to high tech, including time travel and faster-than-light transport, so there have to be some mechanics to deal with all of those things. Although it takes a while to read through, it's an enjoyable read, and as a first time GM, I'm not having any trouble running the game. The combat system seems maybe too complex, but that's the only flaw I'd mention. The rest of the rules are simple and logical. As for "dan with the box"'s comments, at least these guys were honest enough to say flat-out what they believe, instead of spouting a bunch of politically correct b.s. And, you've got to understand that a game system that appears to endorse polytheism (which this one would, if not for the disclaimer) is going to be offensive to many conservative Christians. But, for the concept of the game (every universe ever imagined exists, and people travel between them) to work, the game has to have a somewhat polytheistic set-up. All the gods and goddesses of mythology, as well as those of fictional pantheons like Dragonlance's, have to exist in the game world. So, given the fact that they were bound to offend somebody no matter what, they chose to be up front about their personal beliefs. If you don't like the religious elements of the game, they can be ignored to some extent, just as you could run D&D in a monotheistic or atheistic setting if you wanted to. Overall, I'd highly recommend this book.