For me, I'd make a JRPG in a classic sense like FF10, and prior.

I'd make a game like this.

naturalselection2.com

I would make a spiritual sequel to Zelda 2 the Adventure of Link.

It would use the same formula except itwould be greatly enhanced it. More spells, more dungeons, more items, bigger overworld, etc etc..

I would make an action/adventure game in a fully navigable 3D future-gothic urban environment. The combat system would involve rhythm-music gameplay and the main character (non-customizable!) would essentially dance in combat with moves changing dynamically with your input and more becoming  available as you progress further.

The narrative and context would contribute to this being the first posthuman story told in videogames.

I would choose the soundtrack, duh. 

Open world, action/adventure, RPG. I would want the setting to be futuristic kinda like Dues Ex, but GTA openness in 3rd person. You could go in any building, everything is interactable, and any vehicle you see, can be driven. Also a little simulation like you see in Fable or Assassin's Creed would be neat, like if you see a house you could buy it and change it to your desire.

->I'd make a Metoridvania game. Trying to equally mix exploration parts and 2D fast action, Treasure style boss battles. My main sources of inspiration would be Super Metorid and Alien Soldier.
->I'd like to make an open world 3D survival horror Zombie game (very original) where you can't normaly find wapons (only in very rare cases) but you have to build your own weapons and traps using ordinary usage objects.
->I would make a Kart game, since I love MK but at the same I think each iteration of it has some major flaw, so I'd try to make a game uisng best elements of each game, and also adding some new content and game modes.

RTS on a fanatasy setting/old military one in a different universe.
Or adventure /action one where you are a badguy being balckmailed by a smart girl to protect her from an organization. Not open world but dialogue coices that affect wich levels and paths unlocks and the endings.

Why is there no poll?