I don't mean to bash anyone, but there's a lot of really bad suggestions on this thread.
Here's a list of games that you should NOT pick:
- Platformers, like Donkey Kong or Super Mario. They may be great, they may be clever, but in the end of the day, they will most likely not make a man who already has his mind against gaming, suddenly see the medium as intelectual and strong in storytelling. He may enjoy himself, but he can easily play it off as still being childish entertainment, not a serious medium.
- Shooters. Of any kind. Be it Doom, Call of Duty, or even Half Life. He will, for one thing, likely miss the storytelling aspects of them, and it will not help disprove his argument that games are just violent time wasters. Again, he may be entertained, but they will not convice him that gaming is a medium.
- RPG's. They are long, they are complicated, and giving him an RPG as his first modern gaming experience would be a terrible idea, because he will likely not make good on his promise, and play it through to the end. And eve if he does, he will not sink the time into it that it deserves.
- Japanese games. Most games in consideration here would be JRPG's. It would be a terrible choice, because the stories are really not for everybody, and certainly not for the inexperienced gamer, with no ties or experience to japanese culture. He will, most likely, not like/understand the story.
- Fighters/Racers/Sports games/whatever. Anything without a story, or if a story, the sorriest excuse for one. Again, he will look at them, maybe find them funny, but not consider gaming a relevant medium.
- Strategy games. While they are games that certainly display gaming as more intellectually engaging than "childish etertainment", the stories in them aren't all that good. The games are usually very long, too.
Damn. That's a lot of darn good games we just excluded.
Now here's what you want in the game you show him:
- Accesability. That's the most important part. He has to be able to actually play it, and play it without your help. So, the gameplay must be simple, but still challenging. Keep the rules simple.
- Short lenght. You need to be able to tell him, honestly, that he can complete it within the foreseeable future, even though he is an adult, has other responsibilities, and other hobbies he may want to pursue. Give him something he, as an inexperienced gamer, can complete in at least 8 hours.
- Accesible story. By that I don't mean that you should choose something with a "simple" story, but choose something that doesn't start out with a 5 minute cutscene, and don't require much prior knowledge. And, and this is something I think most people in this thread forgot, it has to be something that can be understood by someone who is not a gamers/geeks. Seriously. A lot of the stories we see in videogames makes much better sense to us, because we are used to that kind of stuff. Maybe we ar eused to it because of movies, or comics, or fantasy/sci-fi novels, or maybe from other videogames. But if you haven't already experienced some of the other "geeky" stuff, then videogames, and their stories, will be harder for you to understand.
- Non-violent. That doesn't just mean you dishing it out, it goes the other way too. Mirrors Edge is a terrible choice, same with MGS. It doesn't matter whether you fire a gun or not. What matters is if ANY guns are fired. Violence, not matter the recipient, means the game is about adrenaline(generalization taken to the extreme, but I hope you know what I mean), and if it's about adrenaline, then it is the games equivalent of action movies. And action movies are NOT what you want to show to someone who doesn't regard movies as a medium.
With those criteria in place, I will sugest: Portal.
It is short, so with effort, he can get through it without regretting your bet, and maybe evven giving up. Tell him how quickly it can be sppedrunned, and tell him how fast normal people complete it. It is completely non-violent for the most part, and the parts where guns ARE fired(the turrets), it is still not about adrenaline and running, but about figuring out how to get past them/deactivate them. The turets are interchangable with a pit, acid, whatever. It also gets going right away, without any lenghty cutscenes or explanations. The story is small, so not that hard to understand, but the beauty is about how it's told, and that will make a great argument in your favour. Also, the gameplay is incredibly simple: 2 portals, and physics. The game is not easy, so he will have to engage his mind(another point that will help your case), but he should be able to grasp the core principles of the gameplay fairly well, so he can pour his concentration into the game, instead of into how it works.
Don't tell him anything about the story. Let him explore it for himself. See if he can figure out what happened at Aperture. Just tell him that all he has to do, is explained in the game. Tell him it's short. And tell him to enjoy it, and promise to pay good attention to it.
If that doesn't change his mind, then nothing will.
if he does, you keep easily say the same about books. If nothing else, a game like layton is basically a book where you have to work to turn the page.
