Defensor

Defensor would be a game for all current platforms that would be a hybrid of the hack and slash, shooter, and tower defense game genres. It would be inspired by games like Sanctum and Plants VS. Zombies, in which the goal is to keep an enemy force from reaching a certain point. This has always been one of my favorite concepts for a game, but I find its rarely executed in a way I really appreciate - I always find myself wishing that there were a tower-defense game something more like Dynasty Warriors, set on a large map with lots of different terrain elements where you could play as incredibly strong characters in over-the-top, immersive action while still bearing the larger battle in mind.

This game would have a style you might call a cross between cartoony, lightly cel-shaded, Shonen Jump-style action and a blockbuster movie. It would also not be very story-driven at all, and so wouldn't be confined to a single theme - the player would have a choice of everything from a sci-fi setting with space ships and laser blasters, to a medieval fantasy setting with longbows, horses, and castles, to a zombie apocalypse.

Gameplay
As I implied earlier, this game would include both elements of a shooter and a straight-up melee battle game. Considering that it would incorporate various types of warfare, it would also include various types of gameplay. For example, it would incorporate third person for sword and shield combat, first person for shooter combat, and so on.

Of course, though, there would be a key tactical element to battle in this game, because half the battle is keeping the larger layout in mind. Before the battle begins, both sides will have a few moments to set up defenses, such as barricades, guardian beasts, turrets, troops, and so on. However, these are simply what each side starts out with; throughout the battle, you can implement other defenses as well if your previous ones fall.

The general object of each battle in Defensor would be to capture or destroy the opposing base, not unlike your average MOBA. Depending on how well one side or the other defenses their base, a battle could end quickly or take at least a half-hour. There would be even more complexity to planning defenses considering it would have a z-axis as well - since this would be a 3D game, there would also be flying defenses, or ones elevated in the air.

Battle Themes
As I mentioned before, this game would have a massive amount of battlefield themes to appeal to as many people's tastes as possible, but there would still be a limit, as with anything else. Each theme, however, would have three preset battlefields to choose from. I'll try to include as many as I think would benefit the game and create variety. Here's the full list:

Medieval
By medieval, in this case, I mean medieval Europe - the kind of settings that remind people of knights, castles, and horses. The defenses for these battles would be more grounded, and fighting would be more melee-oriented than anything else. This would be the most grandiose type of battle, essentially. The three battlefields would be:
 * English Castle
 * French Capital
 * Spanish Palace

Fantasy
Fantasy would be similar to medieval, but it would be more like a fairy tale than real-life warfare. Magic and monsters would be involved, and the environments would be flashier and more idealistic. The three battlefields would be:
 * Forest Hollow
 * Heavenly Valley
 * Elemental Castle

Sci-Fi
Sci-Fi would be a theme focused on the classic depictions of interplanetary battle in things like comic books and space operas; it would be full of advanced weaponry and space vehicles engineered for battle. Some of the fighting would also take place in actual space, somewhat like in Star Wars Battlefront II.
 * Stratospheric Fleet
 * Uncharted Planet
 * Techno Base

Superhero
The superhero theme would be one where you could play as overpowered superhero-esque characters fighting powerful villains and their minions in different maps. These would be by far the most comic-book-ish battles, and would showcase some spectacular effects, like bubble burst effects.
 * Zombie Invasion
 * Mobster War
 * Robot Battle

Ancient Japan
The ancient Japan theme would be in the same vane as the medieval theme, but it would take place in the Eastern Hemisphere instead of the Western. You would see warriors like the samurai, shaolin, and ninjas for fan service.
 * Shogun Fortress
 * Battle-Torn Field
 * Mount Fuji

Futuristic City
The futuristic city theme would be essentially just what it sounds like - battles would take place in highly-advanced cities of the future.
 * Humans vs. Aliens
 * Cyborg War
 * Future Fallout

Anime
The anime theme would appeal to the crowd who are fans of action-packed, explosive, colorful anime. The three battlefield themes would be entirely different, however, and each will be inspired by a different real-life anime.
 * Swords and Spells
 * Machine Revolution
 * Clash of Ninjas

Horror Movie
The horror movie theme wouldn't necessarily be based on actual horror movies - it would be based more on traditional ferocious monsters like vampires, werewolves, and yetis.
 * Castle Dracul
 * Forest of Terror
 * The Graveland

Bonus Theme: Dimensional Admin Easter Egg
On playing through every battlefield in the game once, you unlock a special sandbox battlefield to play around with, which will represent my second easter egg exchange with IsGamer13 and his idea Dimensional Administrator: The Locked Dimension.

The Dimensional Metropolis
The Dimensional Metropolis is essentially the hub world of Dimensional Admin, home to and brainchild of super-powerful twin beings Isaac and Aria, the main protagonists of the game. It is teeming with life and activity at all hours of the day, and has both a surface and underground level that have slightly different appearances, but the major differences are that one is light and one is dark.

This would play into the freeform possibilities of this battlefield. It would have its own set of characters in the form of Isaac and Aria, who in the default form of the stage would be having a battle through the metropolis for fun, as well as special minion characters. However, it would also be free for the player to edit using either time of day, and using a massive selection of templates seen throughout the rest of the game. This would be the way for players to take the excitement of a large-scale battle into their own hands and tweak it to their liking.

Soundtrack
This game's soundtrack would be highly varied to cover all the different themes involved. You would hear everything from actiony gaijin rock for the anime battlefields to imposing orchestral pieces for the medieval and horror movie battlefields. This wouldn't mean, however, that a given theme would be limited to a particular music style - if it were me, I'd take the approach that games like those in the Warriors series do, where you can occasionally hear energetic metal in a fantasy or historical setting.