*leans back in the rocking chair* Well, back when I was a wee lil sprout, games were pretty much all combat. There ain't a complex narrative in Defender, but man, I spent my share of quarters on that one. And yeah, someone mentioned Doom already.
But that said, I think games are better if they're more than just combat. Even Left 4 Dead (to take an example) has a world background, and some basic character development. Sure, it's mostly about shooting zombies, but I do think the story adds to the game.