I'd make a game about an obese, balding, middle aged electrician. The concept being that this guy comes into possession of a nuclear arming key by a freak accident. A Brazilian crime syndicate breaks into his apartment minutes after he discovers the key and by yet another freak incident he manages to kill both of them. He electrocutes one of them using a wall socket and a spool of wire he had for a project of his own and shoots the other one in the collar-bone with the first guys gun. Right after that he calls the police leading to a cinematic where he finds out he is suspect in the murder of three of his neighbors, realizing that he has been framed he breaks away from the police and finally gets away, this is where the game would really start. The thing that I would want to do in the game is to make it as realistic as possible, there would be no HUD and no ammo counter you would have to count the bullets if you had a revolver. Also this guy would not be able to hit anything with a gun past 12 yards, as the situation becomes tense his aim would become more shaky. He wouldn't be able to run for very far, and if he over-exerts himself he might start seeing spots and feel faint, if you continue to over exert him for long periods he might have a heart attack, this is where medication would start to be of great use to the main character, he'd need something to steady his nerves, keep his ticker to an even tempo, maybe even an adrenaline shot. You'd have to stitch up wounds and they would cause realistic hindrances. Obviously a bullet in the wrong place would be game over and it is; the game would be divided into a different number of checkpoints based on difficulty; after every enemy you kill it would auto save during a slow-motion replay of the bullet hitting the enemy. Also no eight shot enemies, you'd probably only have to hit em once as long as you get a torso, head shot or major limb hit, of course a winning shot is difficult because he's not a marine. He'd also have his bag of tools which you can use to disrupt electrical inputs and outputs in all the buildings, vehicles, streetlamps etc. During the course of the game you'd eventually get access to firearms and other such things that a crime syndicate would have lying around, Heroin, probably explosives. The plot line would of course have to have many different options. If you have the opportunity to walk away into anonymity you will get the choice, kinda like way of the samurai, except fat and bald.