Gears of War: You hide behind stuff and occasionally pop out and move to the next hiding spot.
Total War: Watch infinite clones of roughly 20 unique guys line up and hit each other for hundreds of hours.
Crysis: Activate Camo and walk through some (concrete) jungle
WWII Online: Spawn alone, walk 5 miles in real-time towards the nearest battlefield, fall sideways and black out, and repeat (without ever knowing what killed you). As a bonus, lose $15 each month
Dragon Age: Read hundreds of pages about a depressing fictional world, and click some stuff in between.
Mount & Blade: Stab everyone who's not your color to get better stuff for stabbing. When you get tired of that, switch colors and stab everyone who's your original color. When even that gets boring, make your own color and just stab ALL the people. (Note: there are also some fetch quests in there, if you seek them out)