LittleBigPlanet 2 is the game that never ends.
The designers of LBP say that your only limit is your imagination. They're right. The levels and games created in LittleBigPlanet 2 already are simply staggering. I went through a playthrough of several random LBP2 levels yesterday, to introduce Mozz to the game, and the variety is unbelievable. They ranged from First Person Shooters to dungeon-crawlers, to clever and challenging platformers, to fighters, to racing games, to an absolutely stunning piece of gaming art called The Machine That Feeds On Our Dreams. You can create anything in LittleBigPlanet 2. Anything. LBP1 may have provided the promise, but LBP2 delivered the goods.
Every day, more and more levels are being made, and some of them are simply astounding. If you think there are limitations in the editor, the community designers have already busted through them. If you think something can't be done, it's like the community wants to specifically prove you wrong.
Single player? Multiplayer? LBP2 is great at both. The game's story mode features humorous cutscenes and some charming and brilliant levels of its own, and the single-player-only levels in the Community can engross you as much as any other game in the tourney. Try giving In Pursuit Of The Meddling Magpie or Steel City a try and tell me that these aren't GOTY contenders by themselves. And not only are these levels fun in a bun, the entire game becomes exponentially better when playing with a friend, online or offline, designing levels or playing them.
This game has the most replay value of any game, ever, because it literally does not end. There is always new content of all types being generated every second. It will excite and mystify you like no other game.
Super Mario Kart is a mascot racer. It's one done right, and it's fun, but it really is just that. I love Mario, but LBP2 can do racers as well, along with millions of other kinds of levels and games. One spin through the best levels that normal people have created on LBP2 and your mouth will be left hanging open in awe of the genius that some of these designers possess.
Oh, did I forget to mention that it's also incredibly fun?
Super Mario Kart just can't compete.