After more than 20 years of battling Mario and Luigi, Bowser has finally had enough of the plumber brothers. Goombas clearly aren’t getting the job done. Koopa Troopas aren’t strong enough either. Even Bowser’s own fireballs could not push back the continuous Princess-saving onslaught of Mario and Luigi.

But their menace would continue no more. With more anger than all the Mushroom Kingdom inhabitants could imagine, Bowser took a deep breath, ready to unleash a world of pain…and accidentally inhaled Mario and Luigi in the process. Like tiny organisms moving through our own bodies, Mario and Luigi now live inside of Bowser. Together, they must help Bowser stay healthy and strong so that he can inadvertently protect the Mushroom Kingdom from a new threat that could be more powerful than the King Koopa himself.

If the premise of Bowser’s Inside Story sounds like a page out of Dr. Mario, have no fear – this is not a puzzle game. It is a sequel in the Mario & Luigi franchise, albeit with some amusing twists you may not have expected. Granted, this is the zaniest of all the Mario spin-offs. But who could have foreseen a game that would involve one RPG quest with the plumber duo inside of Bowser’s body and another quest with Bowser in the outside world?

The switch between each journey may not be innovative, but it’s certainly creative. As Mario and Luigi, you’re dropped in a dark (but not creepy or eerie) 2D world that involves a mix of side-scrolling exploration and traditional Mario & Luigi-style battles. Shell-ricocheting, fireball-throwing, and well-timed double-jump moves are among the attacks you’ll be able to execute, but there are many more to earn and unlock. New attacks are obtained by collecting puzzle pieces, all of which are (thankfully) marked on the game’s easy-to-read map screen, which can be brought up with a tap of the Select button.

Contrary to the environments inside of Bowser, the world he explores is one of vibrant colors. Utilizing a semi-top-down perspective (which falls somewhere between an isometric view and a top-down view), Bowser’s levels are slightly reminiscent of the old Zelda games. His attacks, of course, are all his own: punching and fire-breathing are his primary weapons, but he’ll gain other attacks along the way. With his fire power, he can burn down trees that block his path, ignite bushes to acquire coins, and initiate combat with enemies as they pass by. (And damage them. As always, enemies are visible on the world map; if you strike before the battle begins, they will receive extra damage.)

Both quests are broken up in a way that cleverly fits within the story. Mario and Luigi tend to be utilized whenever Bowser is injured or needs some more power. When he finds himself without the ability to breathe fire, or when he’s trying to push a very large object out of the way, he’ll unknowingly enlist in the aid of Mario and Luigi. The game switches to their perspective, allowing the player to explore Bowser’s body and find the solution to his current dilemma. The solution may involve a brief journey through Bowser’s arm (in which they’ll have to solve a few basic puzzles, defeat several enemies and eliminate a boss). Sometimes the solution will lead to a mini-game where you have to use Mario and Luigi’s hammers to bounce magic balls off a weakened part of Bowser’s body.

In that sense, you could say that Bowser is the real star of the game since everything the plumbers do is for him. Once he’s in tiptop shape, the King Koopa is free to roam his land and battle enemies of his own. These battles are not unlike the turn-based brawls Mario and Luigi face; in fact, this is where their worlds collide most frequently.

Bowser can use his powerful inhale ability – the same one that allowed him to devour Mario and Luigi – to inhale certain enemies and items. When items are inhaled, you’ve just given yourself a bonus. But when enemies are inhaled, they drop down into Bowser’s body, instantly launching a new combat session with Mario and Luigi. Now, to win the battle up top with Bowser, you must first defeat these enemies with Mario and Luigi.

Graphically and musically, Bowser’s Inside Story remains true to the series’ unrelenting reputation. The visuals won’t blow your mind but the character designs and animations are very well produced. They do go a bit overboard at times – you’ll see Luigi freak out as often as he did when surrounded by ghosts in Luigi’s Mansion – but that speaks to the game’s quirkiness, which is at an all-time high. The story isn’t as humorous as the Paper Mario franchise, but there are some great moments, particularly those involving Goombas.

The score is top-notch – it isn’t as epic as the Final Fantasy franchise, but it merges just the right amount of classic Mario tunes with new music to create a soundtrack that is extremely memorable.

As an RPG, Bowser’s Inside Story gives players a solid amount of stat upgrade features (HP, SP, power, defense, speed and luck), a decent array of equipment, and a frequently updated list of attack opportunities. There are multiple ranks for each character, and a host of other bonuses/upgrades that help push the gameplay away from the path to repetition. The mini-games are a tad boring, but they only take up a very small portion of the game and are very easy to finish. Most of the journey will be spent in true RPG form, with great battles and some of the most unusual environments you’ve ever seen.

Gameplay: 9.0
Stellar, highly engaging turn-based battles that combine two separate journeys into one hugely addictive game. Despite not being a "true" Mario game (it's an RPG, not an action/adventure), this spin-off embodies the essence of the traditional Mario titles, producing an experience that is deeply inspired.

Graphics: 8.2
Bowser's Inside Story could be criticized for using a graphic style that isn't that different from the previous iterations. But if you look at what's there – primarily the animations and individual character designs – the graphics are a standout feature. They don't change the cycle of Nintendo DS graphic design. But in the realm of two dimensions, they make excellent use of the DS' hardware.

Sound: 8.4
Like a trip down memory lane and a journey to something new, Bowser's Inside Story features a score that is rich, catchy, and full of Mario inspiration.

Difficulty: Easy/Medium
Just barely "medium." While the Paper Mario franchise (Mario & Luigi's RPG sibling) has had its challenging moments, Bowser's Inside Story doesn't provide Mario fans with any challenges that we haven't conquered before.

Concept: 8.0
Another game-changing addition to the Mario & Luigi series. The dual quest system was a brilliant move that added a new gameplay dymamic while giving the developers a chance to tell another crazy story.

Overall: 8.8
Mario & Luigi: Bowser's Inside Story has everything you could want from a Mario game: creative levels, likable characters, and most importantly, gameplay that makes it impossible to put down.