Metal Gear Solid: Protagonist with oddly erotic sounding codename and wearing tight spy suits infiltrates and kills terrorist organizations while needlessly complex conspiracies and absurd characters surround him. Also nano-machines explain everything.
Red Dead Redemption: Ride around on your horse for miles and get shot at by bandits endlessly.
Assassin's Creed: Uninteresting main character lives the past lives of his infinitely more cool ancestors through a magic machine only for us to have to focus on him just because he is the main character. There is also a lot of climbing and stabbing.
Call of Duty: Single player: Kill endless waves of Nazis or Russians/Arabs until you are satisfied. America saves the day fuck yeah! Multiplayer: Kill endless waves of enemies until you rage quit or go deaf from all the bratty 13 years old screaming in your ear.
Battlefield: Singleplayer: Same as above. Multiplayer: Spend hours trying to master vehicles that don't do much anyway, I mean seriously those helicopters can't fly for shit.
Crysis: Kill endless waves of Koreans until aliens come out of no where and fuck your shit up.
Halo: Generic action hero defends against alien invasion.
Uncharted: Indiana Jones: The Video Game.
Fallout: Survive in a wasteland wandering dreary, brown environments while endless waves of bandits and mutants shoot at you. Also decide between numerous ambiguously bad choices of government that all seem to be just as bad as the next.
Mario: Chubby plumber, who does no actual plumbing, gets dumb girlfriend continuously captured by a fire breathing turtle-dragon and jumps on top of his various minions' heads to save the day.
Sonic: Blue hedgehog that can run at the speed of sound tries to fight fat guy from taking over the world.