OK, bit of a silly idea this, but not one that's completely out the realm of possibility. Essentially, it is the combination of Nintendo's Mario RPG series (chiefly the original SNES game) and Konami's Suikoden series. Just to be clear, here are the defining gameplay elements of both series:
Mario RPG:
* Closely linked to the famous platformers in terms of characters, worlds, enemies and general graphical and musical style.
* Player Characters have triggers and tend to have powers related to the platformer games.
* In most scenarios, someone other than Bowser is responsible for the current crisis happening to the Mushroom Kingdom. Bowser is usually seen as one of those incompetent recurring bosses, and sometimes even as a Player Character.
* Crisis is usually linked to the Stars (starmen and such) and Mario is required to seek their help/guidance.
Suikoden:
* The basic plot tends to follow a "Hero is an important member of an Empire", "Hero falls afoul of a coup of some kind on the Empire", "Hero spends rest of game finding followers to help fight said Empire", "Hero finds a headquarters to stage wars from", "One of the True Runes is found to be responsible for everything". All of these, besides the True Rune part, can be worked to fit into the world of Mario.
* 108 Characters. Some of which are important to the Plot and others are secret. Most of them are fighters you can use in your party (of six) and the rest just help out some way by selling items, leading troops or providing services for your HQ.
* Game has three separate combat modes: A real-time war strategy mode, a normal RPG attack party comprising of six characters, and a one-on-one duel that the Hero occasionally has to fight against a major enemy character (or sometimes to a friendly character to prove your worth).
* Game also follows a "rock-paper-scissors" system when it comes to warfare and duelling an opponent.
Both of these lists are actually compatible. You could theoretically therefore make a Mario RPG Suikoden game without compromising too much of either series and disappointing fans of either camp.
Because it is Mario, there will be less swords and arrows and things of that nature, which will be replaced by common Mario attacks such as using fireflowers, stomping on enemies or hitting them with hammers.
So for instance, the Suikoden war system of Arrows > Cavalry > Infantry > Arrows could be turned into Spiky Units (those with spikes on their heads, a clear indication not to jump on them) > Jumpers (like Mario, characters that jump on enemies' heads) > Hammer Units (jumpers can avoid thrown hammers, and Hammer Bros are usually vulnerable to being jumped on) > Spiky Units (since they have nothing to protect them from getting hit with hammers). There would be additional "special" units and attacks too, which fit within the above scheme but with several benefits (Mario could use a Fireflower to hit the enemy without worrying about counterattacks, for instance).
If a real-time strategy war game with entire units of hammer-wielding Goombas and Lakitus for air support sounds as awesome to you as it does to me, read on.
The plot of the game will follow the classic Suikoden blueprint: Mario is a well-regarded hero in the Mushroom Kingdom who is good friends with the current ruling monarch Princess Peach. However, some unspeakably malevolent force drops from the skies and stages a coup of Peach's Castle, kidnapping all the senior members of staff and turning the nearby Toad Town into a prison camp. Mario and Luigi barely escape from this catastrophe and must convince the otherwise apathetic neighboring kingdoms to lend their support against this new menace before it is able to gain any more ground and become truly unstoppable.
The game then follows the adventures of Mario and a group of friendly characters as he goes to various kingdoms filled with classic enemies and convinces them to help liberate the world of Super Mario from these evil extraterrestrials. As well as other Toad-populated cities, you can recruit Goomba populations, units of Koopa Troopas (though getting Bowser on your side will be a game-long hassle because of the shared animosity) and even getting the mischeivous Boos to help with their innate stealthy abilities. The player will also be exploring dungeons and the like with his adventuring party to assist potential allies with their problems, find out who these enemies are and how to fight them effectively. He'll also be taking part in various war campaigns to prevent their near-innumerable forces from taking over any more territory.
If possible (or if it becomes too hard to find 108 playable characters using the Mario series alone), other Nintendo game franchises like Zelda could be included as a "neighboring" kingdom, though it would make keeping the game coherent somewhat difficult (since Zelda characters look and act a lot different from Mario characters).
While I doubt anything like this will actually get made, I still submit that it is not impossible. Especially when you consider the original Mario RPG was made with the help of Square (now Square-Enix) and the Mario series' pattern of experimenting with genres outside of the original Platformer format. Of course, if it ever does get made it'll be by two expertly-staffed Japanese gaming giants so there's no way I'll get to work on it in any case. But I'd still like to play it someday.
