You'll never see it coming.
... Let's see. Mario already has motorbiking * , go-kart racing, golf, tennis, baseball, soccer (or American football for you non-American tropers out there), basketball, volleyball, field hockey, ice hockey, and dodgeball, not to mention other sports covered by the three Olympic Games crossovers with Sonic...
American football, maybe?
edited 30th Dec '11 9:11:47 PM by X2X
"Oh no, Sanji's Chronic Simprosis!" - Kou The Mad
Mario Ballet.
Sabertooth
Fortune Street 3D?
3DS FC: 1719-3694-1541
The Fastest Man Alive
A new Mario Hoops? -crosses fingers-
They should revive Yoshi's Cookie.
Easy street has no parking signs.
Mario Bitch Toss.
edited 30th Dec '11 11:32:59 PM by MacDuffy
Mushroom Kingdom Divided, an RTS about a brutal civil war. Will you side with the Royalists, or the Revolutionaries?
edited 30th Dec '11 11:34:27 PM by Talby
Mario Paintball.
Thie video
explores this concept.
Wait a minute. Why has this not been done yet?
A Mario game...
WHERE YOU ACTUALLY PLUMB.
And I don't mean like in Mario Bros where you were getting monsters out of the sewers. I mean like genuine plumbing. Fixing pipes, plunging toilets, al that good stuff.
Easy street has no parking signs.
Do the Plumba!
edited 30th Dec '11 11:53:32 PM by MrDolomite
Burn
White Collar Mario. Enjoy hours of fun sitting in front of a desk, sipping coffee, and yawning as you look over files on endowment plans.
Fight. Struggle. Endure. Suffer. LIVE.
Ridley and Ridley
Mario: The Flamethrower.
Welcome to th:|
I'm an Irene!
Waluigi Land.
Yes, I want a game where he's the main character or key to the plot. Meh.
Quest 64 thread
...What the brown?
Hotel Mario 2: Holiday Inn Edition
You guys like Let's Plays? You guys like shameless plugs? Well, come on down!
TV Tropes' Sonic Wiki Curator
A more traditional Mario / Sonic crossover, perhaps?
Experience has taught me to investigate anything that glows.
There really needs to be an epic Mario and Sonic platformer, blending the gameplay and style of both series into a super mega ultra ultimate game.
Awesomebender
![[up]](https://static.tvtropes.org/pmwiki/pub/smiles/arrow_up.png "[up]"){kind=icon}
...
I would buy that in a heartbeat.
I think American Football would be the most obvious choice, although I don't think it would be as universal which seems to be a big thing. Although, I wouldn't mind seeing a Plumbing game either ![[lol]](https://static.tvtropes.org/pmwiki/pub/images/lol2v12_4863.png "[lol]"){kind=small}
.
Sabertooth
Mario Makes Pizza. Bowser kidnaps the princess and the only way to rescue her is to make pizzas of different sauces and toppings.
3DS FC: 1719-3694-1541
I am making sense!
Let's see... fighting game? Pretty much covered. Luigi's got survival horror. Maybe a FPS? There's been something of a shortage the past few years.
EDIT: ok fps was pretty much mentioned already; I TRY to be original, I TRY
EDIT 2: Mario... plumbing? Final level: looks like Wario was the last one to use the bathroom, and after an all-you-can-eat Mexican buffet at that. Featuring real wiimote plunging action! 
edited 31st Dec '11 4:33:49 PM by ActuallyComma
Except [condescending response follows]. Because [sarcasm here]. You do understand [snark], right? POTHOLE TO SARCASM MODE
You'll never see it coming.
Wrecking Crew 2K12: Now With Actual Plumbing!
"Oh no, Sanji's Chronic Simprosis!" - Kou The Mad
- there is an actual Chess-version with Mario-characters, at least here in Austria. A videogame-version of this would be also neat, though. ^^
A Mario FPS already exists!
Has Mario ever done a tactical RPG? 
I just imagined Disgaea with Mario characters. XD
edited 1st Jan '12 2:26:55 AM by burnpsy
Because every other Nintendo-made system had at least one. There will be one.
What would you want it to be?
Thinking about it, what sport hasn't Red M done yet?
Yep, I'm still here.