Mario and Luigi are teaming up again, but this time their journey takes them on an exploration of Bowser’s insides!

Unveiled at Nintendo’s E3 press conference last night, Mario & Luigi: Bowser’s Inside Story will be available for the DS and DSi this fall. This action RPG begins with Mario and Luigi being inhaled by Bowser after he eats a magic mushroom.

Players are in control of two storylines, one features Bowser trying to stop an arch-villain from taking over his castle, and the other features tiny Mario and Luigi inside Bowser, trying to take control of this fiend and escape.

Players will be able to switch between storylines, but remember that what happens inside Bowser affects his actions on the outside! Mario and Luigi will need to solve puzzles and challenges to help Bowser overcome obstacles on the outside and advance in the game.

Players can also enhance their performances during battles and challenges by making well-timed button presses. Bowser grows so large in some battles that players will need to turn their DS or DSi sideways and blow into the mic or tap on the touch screen to stay in the game.

Take a peek at the debut trailer and first screenshots of the game to get a better idea of how the action works.