The Thousand Year Door. The Gamecube one. I've been playing it for like a month. Gamefly got their money's worth outta me this month.
The one serious flaw with this game is that they require excessive amounts of backtracking. The game is long enough as it is, they really didn't need to do that to artificially extend the playtime.
That said, the game is right up there with Chrono Trigger and Golden Sun for me. Like Golden Sun, there are puzzle elements mixed in with the more standard console-RPG stuff. Unlike Golden Sun, the puzzles felt really fresh. While Golden Sun riffed off Zelda, the puzzles in Paper Mario involved a set of powers and abilities that I mostly haven't seen the like of in a game, and for the most part they were just challenging enough to make me feel clever without being so challenging as to stop me. There were even a couple puzzles I had to work at for a while before getting. When I did get stuck, there are a couple of in-game devices to make it so you don't have to turn to Gamefaqs - you have an advisor character you can ask, and you can sometimes pay game-money for a short walkthrough. I mentioned in a previous entry that puzzle games ought to have their solutions built in like puzzle books...Paper Mario actually does it. I did have to consult gamefaqs a couple times anyhow, though, so the system wasn't quite perfect.
So once upon a time there were 2D RPG's like Ultima III and Final Fantasy. They had an overworld, and when you encountered an icon in the overworld it turned out that icon represented a whole band of badguys. Later, console RPG's went 3D, and suddenly a 3D character in the overworld represented several characters. (Final Fantasy VII, for example.) Was I the only one who thought that was weird? When it was just an icon it was fine for it to represent multiple foes, but when it became a real-looking character in a real-looking world, and you go to this different set or stage to have your fight with multiple characters...bizzarre.
Paper Mario pokes fun at that. When you encounter one of the 2.5D characters in the overworld and then go to fight them on the different set, the different set is represented as a theater - you're on the stage, you have an audience. It's terribly abstract and bizarre and it works. (And you can do your moves stylishly to earn kudos from the audience to power special moves, so it's even gameplay relevant.)
So Paper Mario is like a deconstructionist or postmodern RPG. A lot of its cleverness comes from playing on videogame conventions, whether they're from different games or from the Mario series itself. Man, you wouldn't think that videogames even have enough history that we could start self-referencing like this.
(Although we did some convention-playing ourselves with the Mysterio boss fight in Spider-Man 2. Some people "laughed their asses off" - one review said "best boss fight ever" - others said "that wasn't even a boss!")
So my dad, not a gamer at all, unless you count bridge, was down in LA to visit his granddaughter, and was in the room while I was playing. And he started watching. And he kept watching. Somehow, this game was entertaining him, even though he wasn't playing.
"Isn't this a little young for you?" he asked.
"It's like a Disney movie," I said. "For kids, but adults can enjoy it too."
Still, he didn't stop watching. He even laughed a few times. When I handed him the controller so I could hold Sofi, he got himself killed very quickly. I'm sure that's just because he was dropped in the middle, and if he played from the beginning it would have been smoother.
(I personally think Nintendo should pull a Disney and come up with a new brand name for their T and M rated games.)
My favorite bit - about halfway into the game - you're facing a shapeshifter boss, who takes on your form, a purple shadow-you. You beat him, they do the boss finale UI, and you - still in control of Mario - leave his crumpled body and go to the next room.
But instead of fading out and fading in to the next room, like it always does, it remains on the same screen.
What's going on? Did it hang? The music's still playing.
You touch the joystick again, and the purple crumpled body stands up. You're controlling purple Mario. What happened?
After a while you realize it: the shapeshifter replaced you. He's gone off with your companions, and you're alone. And purple. And the chapter isn't really over, you need to somehow get your body back.
Of course your companions don't recognize you when you come across the imposter and try to fight him to get your body back. They team up to protect him.
Very clever stuff.