Mario RTS, an idea I've been tinkering on since the N64 days. The Wii's controls can really make it a great game.
There are a number of different factions that the player can command:
Mini-Mario Milita
The "good" faction. They're not quite as mini as the ones seen in past games, these are new bigger & more durable models built for combat. Ground forces are their strong point with the hammer, fireball & Yoshi rider units as the main infantry, Mini-Peaches as healers plus karts & MP5's Super Duel tanks as the heavy armor. In air & sea they're a bit weaker, using mass productions of the Sky Pop & Sea Pop but not a lot else.
Koopa Troop
The obvious villain army. Their ground units are weak (heck, the tanks are made of wood!) but make up for it with cheap prices. The air force is much more considerable with the huge airships making a long awaited return (The complete unit/building list I have for this faction is very heavily based on SMB3) along with Lakitus & other misc. air units. The Koopas also have the best defensive structures with Bill Blasters, Torpedo Teds & Venus Firetraps.
The Tri-harder Alliance
The wild card faction. General Guy, Goomboss & Big Bom-Bomb have had it with Bowser's constant failures & decided to take matters into their own hands, forming their own army & declaring war on both the Mushroom & Koopa kingdoms. Between the diversity of the Shy Guys, the heavy firepower of the bom-bombs & the mass numbers of the goombas, they feel they have what it takes to conquer the world. Their biggest weakness is the limited base defenses, they only have chain chomps which are only good on infantry.
Controls
The Wiimote's point is used to click on units & buildings or to select whole groups of units. A pop up build menu can be accessed at any time for ease of construction/training. The nunchuck operates a bit indepenently of the remote, it's used to control the player's chosen commander with platformer like functions.
Commanders
Basically who the player assumes the role of, they are established characters in the Mario universe that can fight well on their own & grant different bonues to friendly units they're grouped with. The Mini-Marios have Mario (duh), Luigi & Peach while the Koopa Troopa gets Bowser, Bowser Jr. & Kammy. The Tri-harder Alliance lives up to it's name by having more commanders than the other 2 sides. In addition to the main 3 rulers, they employ mercenary commanders like Wario & Captain Syrup.
Resource management
To help streamline the micromanagement aspects of the RTS genre, there's only 1 type of resource: coins. They can be collected by any units & they're instantly added to the player's bank account without need of sending the unit back to base. Units leave behind coins when they die like in past Mario games so players can recover from losses in big battles.
Civilians
Toads, shelless koopas & docile goombas, these are the citizens that populate each kingdom that the players are tasked with protecting on most campaign & multiplayer maps. While they can't be directly controlled they can still be helpful. Town mayors may decide to donate funds to the player, mothers bake food that can boost the stats of a commander, rascaly children lay traps, hosbitals can heal infantry & braver men will take up arms if their homes are attacked. There's also reasons to assault the enemy's town without intentions of wiping it out. Destroying the bank will net some quick cash while destruction of the local jail busts out free infantry units.