Koopa Krusades

You play the role of a young Koopa Troopa enlisting in the ranks of King Koopa's legions.  The game would be an RPG where your initial goals are to defend the Koopa Kingdom from monsters and other malicious forces.  It isn't long before King Koopa declares war and invades the Mushroom Kingdom.  During the course of which you would clash with the famous plumbers themselves, Mario and Luigi, and encounter many famous Mario characters.  

Your character would start out as an ordinary Koopa Troopa however later he would acquire other classes and abilities.  For example, the gift of a Hammer Bros. hammer would allow him to transform into a full-fledged member of the Hammer Bros. and the Paratroopa shell would allow him to transform into a Paratroopa.  You have your own base stats but each form gives new abilities and depending on what forms you spend time leveling, you gain synergy powers such as Hammer Quake--a diving attack that puts the power of the Paratroopa's wings into combination with the Hammer Bros. hammer to slam the ground with such incredible force that it damages and knocks down all enemies.

You wouldn't be alone however.  Many familiar faces of foes Mario has battled in the past may accompany you depending on the choices you make throughout the game.  Old faces like Chain Chomp and Shy Guy will of course make appearances however even some newer faces like Blizzaurus may as also appear.  All of them will have their own unique powers, abilities, and level progression letting you customize their abilities to suit your playstyle.  They will also have their own opinions and reactions to the story's path and your choices.

And of course, there will be replay value.  The game will feature a 50 hour main story with over 60 additional hours of sidequests and a whopping 8 endings depending on the player's choices.  There will also be a New Game+ which will contain new story paths as well as additional powers such as maybe even a Mario cap (I wonder what that might do...). 

It will be a long and harsh quest for our little Koopa Troopa but it will be one filled with action, adventure, and excitement around every corner.

Nice idea.  So would it play more like Super Mario RPG or Paper Mario N64/GCN?

Yea, I am almost done with PM:TTYD and most my upgrades went to badges (Badge points are just so damn tempting especially when you get a bunch of cool badges that you want to equip) , then FP, and a few into HP.