Even if it were just a plain old Mario Kart-style kart racer, ModNation Racers would still be pretty fun. But it's the robust set of content-creation tools, and all the absurdity they enable, that make the game really memorable. ModNation provides a good mix of madcap weapon-based racing action with actual depth, and the sort of gleeful large-scale copyright infringement that only user-generated content can provide. As long as Sony's legal department doesn't get involved, this game will let you race as many tracks using as many characters and karts as you can download or create yourself.
There's nothing too surprising about the core kart-racin' formula here. You drift around curves, kicking up sparks as you go, and pick up weapons from little power-up boxes scattered around the track. Those weapons mostly fit into archetypal red shell-style categories, but you can power each weapon up by picking up extra boxes before you use it to change its properties and make it more devastating. The best thing about the racing system is the boost meter. You build it up slowly by doing anything the game considers a trick--powersliding, drafting, midair 360s, and so on--and then cash it in to... go faster. Crazy, right?
But that's not all the boost meter is useful for. You can also use it to create an energy shield around your kart, which is crucial when you're about to get hit with something you can't avoid, like a homing missile. You can also cash in a chunk of the meter to physically kart-check a driver on either side of you. So there's a fast-paced risk/reward system at work here that encourages you to do tricks as often as possible to keep your boost meter high, and then makes you intelligently decide whether you want to use the meter offensively to get ahead, or save it up to save your butt when you're under attack.
ModNation has your standard run of racing modes: career, quick race, and online multiplayer races that you can play as simple pick-up races or as "XP" races that will level up your persistent online dude. There are enough pre-made tracks included with the game to keep you busy for a while, and every career race has a number of pretty demanding challenges attached to it--stuff like "rack up 140,000 drift points" or "take out three opponents with a level 3 weapon"--that make them worth replaying, especially since each challenge unlocks plenty of trinkets like new clothing and accessories, track parts, not to mention entire new karts, when you meet them.
If you never took ModNation Racers online, you'd mostly miss the point, though. The game's default vinyl-figure-looking characters and tracks don't have a ton of personality to them. They get the job done, but in a genre where character heavyweights like Mario and Sonic hold sway, these nameless dudes don't really cut it. That's why ModNation demands that you hit the Internet and see all the truly ludicrous, random tracks, karts, and drivers (called mods) that the community has cooked up. The creation tools for all categories offer as much complexity as you want to make use of, and the more time you want to put in, the better the results you'll get. There's next to no learning curve with these tools, though; if you want to just try your hand at making a new mod, it's easy enough to make a cool-looking dude even if you don't want to shape primitives into facial features or tweak the scale and orientation of the eyes. The track editor is similarly easy to use; you can lay down track with an interface that's almost as easy as driving on it, and the game will auto-populate your course with props if you don't want to set them all by hand.
In full disclosure, I really couldn't care less about making my own stuff in a game like this. But that doesn't matter, because plenty of creative people are already out there, cranking out tons of neat stuff to download. Would you like to race with Vault Boy driving the car from Monopoly on a pretty good recreation of Ghost Valley 1 from the original Super Mario Kart? How about Space Ghost at the wheel of Optimus Prime? Old Snake in the Scooby Doo Mystery Machine? The van from The A-Team? A track that will hook you up with the 1080-spin trophy almost instantly? All that stuff is already available for quick download in the game, only a day or two after it hit shelves. Heck, there's already a Giant Bomb-themed mod available, and can a Lucha-kart be far behind? Why am I not giving this game five stars again?
Mainly because ModNation Racers has some unfortunate technical issues holding it back at the moment. For whatever reason, the load times range from barely tolerable to atrocious. It can take what seems like forever to get into an actual career race, and even accessing the game's main menu--which you navigate by driving around in it--makes you stare at a slowly moving loading percentage. (That's extra baffling since you can also access all of the same functionality from a traditional pop-up menu once you're in this lobby area.) The game's performance can also hitch up here and there, and I got disconnected from the online servers off and on, but those things mostly only happened in that lobby area. It would have been nice to toggle that off and just do everything from a standard menu, but hopefully these things will be ironed out as the online support matures.
My only fear about ModNation Racers is that copyright will soon prevail and Sony will go in and remove a lot of the craziness from the game's online network. The framework for a raucous multiplayer experience is in place here, and as long as the community's wacky laissez-faire attitude toward user-created content is allowed to persist, ModNation Racers will be an amusing kart-racing sandbox to drive around in.