The king of koopas has been causing trouble for everyone in the Mushroom Kingdom for as long as we can remember, but in Mario & Luigi: Bowser's Inside Story for the Nintendo DS, the real nemesis is Fawful, a delusional and deranged bean that floats around on a hovercraft. It looks like developer AlphaDream has once again crafted a high-quality and memorable role-playing game, using a set of characters that we've all gotten to know very well over the years. We had a chance to play a quick demo at the 2009 Electronic Entertainment Expo and had a great time with it, so we were looking forward to playing with a new preview build. After spending a few hours with the game, we were quite pleased with it as well as fascinated by how the piping works inside Bowser's belly.

　　You're probably wondering how our favorite plumbers ended up in the big guy's stomach in the first place. As the story begins, we learn that the citizens of the Mushroom Kingdom have been afflicted with the "blorbs," an odd disease contracted by eating a mysterious mushroom. Toads from all over the kingdom have ballooned to the point where they've become giant roly-polies. Princess Peach calls a meeting to figure out what to do, and of course Bowser shows up to ruin the party. Mario quickly disposes of the giant koopa, and Peach sends Bowser packing by transporting him into a forest, where he meets Fawful in disguise. He is easily suckered into eating a "lucky mushroom," when in fact it's a vacuum mushroom. The not-so-smart koopa returns to the castle and proceeds to suck up everything and everyone until he falls unconscious. When he wakes up, he has no recollection of inhaling the entire meeting room, but he knows that Fawful is up to no good and therefore must be kicked out of the kingdom.

　　You'll rotate between playing as the hulking reptile and as the mustachioed brothers, who are stuck inside Bowser's tummy. As Bowser, you'll be punching and breathing fire as you rampage angrily around the kingdom, trying to track down Fawful. As the brothers, you'll need to find the princess (and the other members of the council that were ingested), while platforming your way through Bowser's innards. The top screen is where you'll control Bowser, and the touch screen is where the plumbers' actions will unfold. There's a lot of collaboration going on that requires you to switch back and forth between the two screens. For example, when Bowser drinks, his belly will fill up with water, allowing Mario and Luigi to swim to otherwise inaccessible areas. To give Bowser a boost, Mario and Luigi can head over to his arm and swing balls of light into his muscle tissue to increase his strength. This is probably going to be one of those rare moments that we'll see this much teamwork between the big koopa and the plumbers.

　　Like in previous games, Mario and Luigi are controlled with the A and B buttons respectively. Battles are a mix of turn-based and real-time movements, so you'll always need to be on your toes if you want to avoid taking damage or get an extra attack in. It's all about timing, whether you're attacking or defending, and each enemy has a particular attack pattern to watch for. The two brothers can jump or wield hammers to deflect blows, whereas Bowser can punch or duck oncoming attacks. You can easily counterattack, and when done right, it makes battles go by more swiftly. With Bowser's vacuum ability, you can inhale smaller creatures, and once he does, the brothers can lend a hand by dealing damage from within--it's like playing two different games at once. As you progress through the game, you'll also learn special abilities. Mario and Luigi can combine their efforts and attack with a green shell, whereas Bowser can send a swarm of flaming goombas into battle, as long as you light them with your stylus beforehand. These special attacks take up skill points, but they make battles so much more interesting.

　　This is what happens when you get the blorbs.

　　All the elements of a traditional RPG are here, except they've been toned down so that you're not always leveling, managing equipment, or dealing with statistics. The stylus will be used in certain special attacks or minigames, but from what we've played, you're primarily using the D pad and face buttons. It's a simple setup, but the gameplay is fun, and the quirky humor and charming characters are just two of the reasons fans continue to follow the series. You'll come across familiar faces from the many adventures that the brothers have been on, only now you're fighting from a slightly different perspective.

　　You don't need to have played the previous games to dive into Bowser's gut. But if you're ready to tickle the cranky koopa's funny bone, be sure to stay tuned for our full review when Mario & Luigi: Bowser's Inside Story is released on September 14.