Your Frankenstein Game Creation

[NooNameLeft]

Chivalry Medival Warfare combined with Natural Selection 2 + Age of Empires
one player is the commander like in NS2 and the other players and the units fighting with CMW combat system.

Perfection.

 

[Imperioratorex Caprae]

I'll go this route:

Red Faction's GeoMod technology (expanded to work on everything)
Elder Scrolls/Just Cause 2 style Open world mix (large map, buildings = free roam)
MGS3's quality of story.
SpecOPS the Line's right turn morality.

 

[Hagi]

An open fantasy world like Skyrim and an open 'real' world like GTA. Linked through some magical portal you can use to travel in between them.

Got a dragon problem in the fantasy world? Hijack a jet from the real world and use some air-to-air missiles to take them down.
Facing heavily armed resistance in the real world? Learn telekinesis in the fantasy world and stop bullets with your mind!
Fighting a necromancer raising an army of zombies in the fantasy world? A chainsaw from the real one is just the answer!
An enemy boss in the real world has his base of operations on a freaking aircraft carrier? SUMMON THE KRAKEN from the fantasy world!

 

[lRookiel]

Mount and Blade gameplay
quests and story by Obsidian/ someone that can write a good story, I don't care who.
Modded Skyrim graphics
completely modable

I'd never need another game.

Oh yes.

I'd throw in some Dark souls difficulty as well.

 

[Icyheart]

An Elder Scrolls world with Shadow of the Colossus monsters and fights on the overworld, and Assassin's Creed-type free-running and parkour in the cities. Only problem is you'd have to be in third person to play those last two, but I think it'd be worth it.

 

[MiskWisk]

Let's see.
An Elder Scrolls open world, futuristic setting, space fighter combat from Star Wars Battlefront 2, large ship management if you want something bigger than a fighter (unfortunately I do not have a good example of this), a story written by pre EA Bioware and a San Andreas jetpack. That would make me very happy. Shame to fit all of it in you'd probably need a super computer.

Edit: And a decent interplanetary travel system (again, no good examples)

 

[Brainwreck]

An Elder Scrolls game, made by Obsidian in triple the usual time they get.

 

[The Undoer]

An Elder Scrolls game with a story written by Michael Kirkbride, music by Jeremy Soule and Clint Mansell, graphics comparable easily to Skyrim with modded graphics, and Witcher 2 style of combat, Half Life 2 physics, Mass Effect quality characters, Deus Ex' mystery, and Fallout companion system. Oh, and way more armour and weapons, and a map spanning the entirety of Tamriel.