Shy Guy Racing

 Shy Guy Racing would be a racing game published by Nintendo for the Wii U and 3DS that would serve as a spinoff of the immensely popular Mario Kart series. The most important difference would be that instead of a roster full of different Super Mario characters, the roster would consist only of different Shy Guys, which are part of a species within the series.

However, there would be more than just cosmetic differences; the game would incorporate interesting gameplay/level design mechanics, and would be similar to Sonic and All-Stars Racing Transformed, because choosing different characters would have a definite impact on your gameplay experience through things like receiving particular power-ups more often than others.

Gameplay
Being a spinoff of Mario Kart, this game would play in much the same way as recent games like Mario Kart Wii or 7. However, my idea for the game is to give it more...voluminous tracks. They would be a bit larger in general, and would be longer than tracks in these recent titles. Someone would be shorter than others, of course, and they wouldn't be so long that they would be-labor every single race, but there wouldn't be significantly short races.

The game would also stress incredibly tight control, such that it would be very realistically like driving a go-kart. I also think that it would be interesting if movement speed were a bit faster in general, just to achieve that same goal of a satisfying racing experience, but it wouldn't be so drastic a change that everything would feel out of control.

Otherwise, Shy Guy Racing would be set up like a standard Mario Kart, as I said before. There would be various kart customization options from Mario Kart 7, and in my vision, the hangliding function from that same game would return in this one, along with toggling first- and third-person racing with a button press. However, I like the idea of having a few extended hangliding sections in the game, to mimic the flight segments in Sonic and Sega All-Stars Racing Transformed.

Lastly, there may be some instances where anti-gravity racing from Mario Kart U might be implemented, simply to add even greater variation in gameplay experience. Most likely, it would be activated and deactivated by special panels or barriers on certain routes in the track that the player must consciously take.

Characters
As I mentioned before, the roster of Shy Guy Racing will be exclusively Shy Guys, but this will not mean that all characters will be the same. There are actually many distinctive Shy Guys, created by things like color and held items, and these will influence their characters' stats and power-ups.

It should also be noted that almost all the special power-ups are actually existing power-ups that all the racers could potentially get; however, this does not reduce their usefulness, because the special power-up of any given character effectively doubles the likelihood of getting a particular power-up during a race. For example, if a given player gets the most use out of green shells than anything else, he/she might want to choose a character with a green shell as their special power-up. This way, he/she has double the chance to get a green shell at any one point in the race.

Starters

 * Red Guy - Special power-up: Red Shell
 * Blue Guy - Special power-up: Blue Shell
 * Yellow Guy - Special power-up: Golden Mushroom
 * Green Guy - Special power-up: Green Shell
 * Snifit - Special power-up: Mask Cannon (provides the temporary ability to shoot small, rapid-fire bullets out of your Shy Guy's mask)
 * Beezo - Special power-up: Bee Wings (temporarily allows its user to automatically hover over gaps and ledges on the track)
 * Boom Guy - Special power-up: Bob-Ombs
 * Groove Guy - Special power-up: Starman

Unlockables

 * Fly Guy - Special power-up: Propeller Hat (temporarily allows the user to use a propeller to fly over grounded hazards and obstacles)
 * Fawful Guy - Special power-up: Lightning Bolt
 * Boo Guy - Special power-up: Boo Shroom (makes its user temporarily ethereal and invulnerable to attack, and also able to "scare" any racers that touch him/her, making them more more slowly for a few seconds)
 * Pyro Guy - Special power-up: Fire Flower
 * Greaper - Special power-up: Boomerang Scythe (a curvy, throwable scythe that moves in a circular pattern in front of its user, spinning out any racers it hits.  It can only be used once per pickup, but is very useful under the right circumstances.)
 * Paint Guy - Special power-up: Paint Splatter (covers the portion of the track directly ahead of the player with paint splotches that temporarily make steering much more difficult for any racer that touches them)
 * Gourmet Guy - Special power-up: Throwing Pies (act somewhat like non-ricocheting green shells and obscure the view of anyone who gets hit by them)
 * General Guy - Special power-up: Bullet Bill

Character Stats
The character stats will be set up in a way rather similar to Sonic and All-Stars Racing Transformed: very simple and straightforward, but important. I say this because all stats will range from 1 to 5 in size, but while this may make them easier to interpret, it means that subtle differences in every stat will mean significant differences on the track, thus making it necessary to really think through your choice of character.
 * Red Guy -  Speed: 5  Acceleration: 3  Handling: 2  Drifting: 4   Weight: 2  Boost: 3.
 * Blue Guy -  Speed: 4  Acceleration: 5  Handling: 4  Drifting: 3  Weight: 2  Boost: 2.
 * Yellow Guy -  Speed: 3  Acceleration: 3  Handling: 5  Drifting: 4  Weight: 2  Boost: 2.
 * Green Guy -  Speed: 3  Acceleration: 4  Handling: 3  Drifting: 5  Weight: 2  Boost: 3.
 * Snifit -  Speed: 4  Acceleration: 3  Handling: 2  Drifting: 4  Weight: 3  Boost: 4.
 * Beezo -  Speed: 5  Acceleration: 4  Handling: 3  Drifting: 3  Weight: 2  Boost: 4.
 * Fly Guy -  Speed: 4  Acceleration: 4  Handling: 2  Drifting: 4  Weight: 1  Boost: 5.
 * Fawful Guy -  Speed: 5  Acceleration: 3  Handling: 4  Drifting: 2  Weight: 2  Boost: 4.
 * Boo Guy -  Speed: 2  Acceleration: 3  Handling: 4  Drifting: 5  Weight: 1  Boost: 3.
 * Boom Guy -  Speed: 3  Acceleration: 3  Handling: 3  Drifting: 3  Weight: 4  Boost: 5.
 * Groove Guy -  Speed: 4  Acceleration: 4  Handling: 4  Drifting: 2  Weight: 1  Boost: 2.
 * Pyro Guy -  Speed: 5  Acceleration: 2  Handling: 3  Drifting: 5  Weight: 3  Boost: 5.
 * Greaper -  Speed: 3  Acceleration: 4  Handling: 3  Drifting: 4  Weight: 3  Boost: 4.
 * Paint Guy -  Speed: 2  Acceleration: 4  Handling: 2  Drifting: 4  Weight: 4  Boost: 3.
 * Gourmet Guy -  Speed: 2  Acceleration: 2  Handling: 3  Drifting: 5  Weight: 5  Boost: 3.
 * General Guy -  Speed: 4  Acceleration: 3  Handling: 2  Drifting: 4  Weight: 4  Boost: 5.

Shell Cup

 * Sarasa Circuit
 * Toad Park
 * Loopdeloop Speedway
 * Goomba Highway

Bob-Omb Cup

 * Comet Observatory
 * Forest Treeway
 * Shy Guy Plains
 * Peach's Castle

Spiny Shell Cup

 * Gusty Garden
 * Honeycomb Road
 * Toy Land
 * Crab Island

Thunder Cup

 * Ricco Harbor
 * Icy Cavern
 * Old Clockworks
 * Bowser's Airship

Mushroom Cup

 * Choco Island
 * Music Park
 * Dino Dino Jungle
 * Mario Circuit

Flower Cup

 * Mushroom Bridge
 * DK Jungle
 * Ghost Valley
 * Shy Guy Bazaar

Banana Cup

 * Delfino Square
 * Moonview Highway
 * Kalimari Desert
 * Wario Colosseum

Star Cup

 * DK Mountain
 * Waluigi Pinball
 * Grumble Volcano
 * Rainbow Road