aka: "The Adventures of Monseuir Turtle Bits"
The story goes, that the mushroom folk are suffering from the Blorbs which causes them all to swell up to the size of boulders and can't move. Peach calls and emergency meeting to discuss what to do about this epidemic when Bowser shows up doing what he does best. Mario and Luigi beat him up and toss him out the castle to where Bowser finds a strange man who gives him a magic mushroom which causes Bowser to inhale the entire royal court. The villian reveals himself as Fawful who has now moved up from sidekick to Big Bad and I like him in this game. He's sort of like a James Bond villian with his strange invention and crazy antarchist schemes to conquer both kingdoms.
So this game is clearly broken up into two types of gameplay. You're stomping around the surface as Bowser and swimming around in his bowels with Mario and Luigi which is weird and funny all at the same time. While the game may be part of the "Mario and Luigi" series, Bowser is the star here and honestly it's great. Sure playing as him was fun in past game's but here he takes center stage. There is a problem is that Bowser is so overpowered that playing with him is almost a bit too easy. He can punch and shoot fire as well as learn's special attacks that allow him to summon minions which is fun but he's so overpowered that you'll end up only using the minions for the higher level boss fights. What's also funny is Bowser has the power to inhale smaller baddies which go into his stomach and Mario and Luigi fight them which adds a level of depth to the turn based gameplay.
As for the bros. If you played the previous two Mario and Luigi games then you will be familiar with the combat. The bros have a series of good moves and now have some attacks that affect all enemies on screen such as Mario feeding Luigi a basket of food to make him grow huge and slam to the ground. But at times I still get annoyed that the game relies a bit too much on perfectly timed dodges and hits.
Also spending a good deal of the game inside Bowser the brothers will often do little mini games to help their foe along like pumping his muscles to make him stronger, or bouncing around in his sinuses to make him sneeze (ewww). Though some of these games drag on a bit too long and can get frustrating.
Another part that's fun but only occurs a few times is when Bowser is crushed by something and on the verge of death. Mario and Luigi will retreat to his crotch area and play a schump to kick start him again which will cause Bowser to grow huge and you turn the DS sideways for a touch based fight that involves punching a foe and blowing into the mic to breathe fire. Not such a good one to play in public but fun nonetheless.
Eventually Mario and Luigi will be able to exit Bowser through pipes depriving us of seeing them crawl out his open sphincter or mouth and they can explore the surface as well.
The game has cute, colorful cartoony graphics and a great sense of humor about itself though not as strong as other games but still enjoyable.
Playing as Bowser= epic win.