Transforming a platformer into an RPG never did seem like an easy recipe for success, but somehow the Mario series has caught this rare form of lightning in a bottle not only once, not only twice, but three times over. The classic SNES title Super Mario RPG: Legend of the Seven Stars established a winning formula of comedy, adventure and unique gameplay which has continued on to this day, and now two different series carry the torch for Mario's RPG outings; both known for their strong writing, fun mechanics and colourful settings. When these worlds collide it's about as manic as you might expect.

Announced at this year's E3, Mario & Luigi: Paper Jam - called Mario & Luigi: Paper Jam Bros. in Europe - is the second title from AlphaDream on 3DS, but there's more than a little extra star power this time around. In the surprise crossover of the year the adorable Paper Mario crew are along for the ride as well, bringing half their kingdom with them. How does it all happen? Well, we open as ever in Peach's castle, where a curious Toad is wandering around a draughty storage room with Luigi. It instantly sets up a charming atmosphere with a fun rendition of the Luigi's Mansion theme and a silly mission to catch a stray mouse. Of course it isn't long until our clumsy hero stumbles across a magic book, which promptly unleashes (or...unfolds?) the entire paper-thin population of a parallel Mushroom Kingdom into the sky.

Paper Goombas and Toads alike are left to fall all across the land, excited and terrified in equal measure. When a paper Princess Peach arrives things really get interesting - as famous characters are introduced to their inter-dimensional counterparts for the first time. Even Bowser gets his own paper rival, and once they're done arguing both of them inevitably team up to kidnap their own personal Princess. It's about as much story as is needed to get the concept moving, basically explaining the Paper Mario series as taking place within a parallel world. Works for us!

After spending a good chunk of time with the game, we'll start by saying this is definitely a Mario & Luigi title at its core. There are absolutely some new mechanics and visual effects that make great use of the paper characters and environments, but it's rooted firmly in a three-dimensional Mushroom Kingdom. Anyone who's played Dream Team in particular will feel right at home, though some pretty interesting changes have been implemented to keep some of the best features of both series'.

Paper Mario himself is rendered beautifully in all his mute quirkiness, and it makes for some funny scenes where the Bros' babbling discussions are met with blank stares from their new companion. Adding a third character into the mix feels like one of the biggest changes made to date, and it has an equal effect on combat and movement. Exploring as a party of three means timing your jumps differently, as Paper Mario is now linked to the 'Y' button for all actions. It takes a bit of getting used to, especially when dodging attacks in the middle of a battle, but it feels totally natural after a little practice.

Combat has been re-invigorated by our new pal as well, with the Bros now arranged in a triangular formation during battle. Paper Mario sticks to the back, boasting some unique abilities that mesh perfectly with the typical "jump-hammer-dodge" system we're used to. By making up to six copies of himself he ends up packing more of a punch than ever, able to split up and hammer multiple enemies at once to create valuable openings for further attacks. On top of that he can also initiate some of the game's most powerful moves - Trio Attacks. These are like super-charged Bros attacks that involve all three characters and a whole lot of paper. Copies also soak up damage, though it takes a full turn to create more. Rather than feeling overpowered, it's been designed to compliment Mario and Luigi's traditional attack by creating opportunities and covering for them when necessary. A powerful ally indeed.

The environments themselves have been fairly traditional so far, moving from green fields into a desert setting complete with dreary underground grotto. Enemies - whether paper or otherwise - still roam around looking for trouble, but our favourite moments are when seemingly open landscapes are quickly made more complex by the arrival of new cardboard structures. Courtesy of Kamek, these sudden changes help blur the line between dimensions, and we hope to see many more examples of them quite literally popping up as we progress.

The Toad hunt which we saw demoed at E3 is actually part of a much broader quest system that's totally new to the series. Certain sections of the game play out as isolated challenges, and completing them adds to the total amount of paper Toads you've saved. For example, you might need to rescue several of them within the time limit, break blocks in a Jenga-esque balancing act to free them, or herd a panicked group to safety. You'll either come across these yourself or visit a Lakitu center to choose from a list of available missions. There's been plenty of variety so far, especially since you can replay quests at a harder difficulty, though we especially love being able to sprint with 'x' and tackle the poor guys to the ground. It's just too satisfying for us to feel guilty.

As we previously reported, the game also supports a bunch of different amiibo from the Mario series. They're used to create character cards, another new system that's designed to help out in battle. It left us scratching our heads slightly as we tried to work out the specifics as to how it all worked, but essentially it's rather like building your own deck of special abilities, with each amiibo generating a different variety. You either purchase or earn a blank card in-game, and then use an amiibo to bring it to life. We were able to test with Bowser and Yoshi; the former creating attack cards while the latter granted a stat boost or cured our team of status conditions. You can use these cards once per battle, though we'd be more excited if it weren't so cumbersome and fiddly. Even after registering the amiibo and generating your ability cards, you need to have it with you ready to scan again whenever you want to use one of them. For a portable title this could potentially make it a bit too much hassle, especially if you're playing on the move.

There are a host of other tweaks that help this entry feel distinct. Enemies now display a level value beneath their names, showing how strong they are compared to your team. An "emergency block" acts as a last minute form of defense, giving you the option to brace yourself in order to take less damage from attacks if you can't dodge them entirely. Choosing a bonus stat to improve for each level up isn't possible anymore, but more powerful rank up bonuses remain that can only be applied once per five levels or so.

This isn't even to mention the boss fights where you'll hop onto a giant papercraft Mario and battle hordes of enemies in an arcade-style brawl! Like Dream Team's giant Luigi sections, these break up the usual gameplay with a completely new control scheme built around charging enemies while avoiding their attacks. They're excellent, tank-like confrontations with real weight to them - ironically enough.

All of this amounts to something ambitious yet familiar; this is a Mario & Luigi game through and through with some surprising new features that have us excited to play more. You're frequently reminded that the Bros. are dealing with two armies this time around, and the journey ahead is made out to seem more arduous than ever as a result. Bowser's Castle constantly looms in the distance, as the game pans forward to keep it at the back of your mind. The setup might be a simple one so far, but we bet there's plenty hidden with the pages of Paper Jam.