First, let me say that I largely agree with your point. I totally agree that violence does not inherently make things less mature. However, it seems that your particular sticking point is MGS, so let me delve into that a bit. I do feel it's less painful than others mentioned, however, keep this in mind:

Metal Gear Solid is a series of games about a cloned super spy that chases down, among other people, another clone that happens to be the president of the United States and a robot psychic. These people can very effectively be called "bosses" or even "super villains." Outside these bosses, the heroic cloned super spy kills dozens or even hundreds of people during a single mission. There are lines such as "Snake, do you think love can bloom on the battlefield?" that personally make me cringe.

As you can see, I have some pretty serious misgivings about MGS' plot, but with all that said, I love MGS' playstyle. I think it's creative, intelligent, and some of the best gameplay ever created. I just think the plot is a bit melodramatic.

And Quickdraw, I do largely agree that violence isn't inherently bad. Heck, there was violence in Shakespeare, and many of the best movies ever made involve wars (although generally speaking, they don't involve a single soldier killing dozens if not hundreds of enemy soldiers, as most WWII era video games do).

So instead of saying that all violence is automatically immature, I'd say that it tends to be, especially when coupled with space aliens and spies and convoluted plots. Is it possible that some day, someone will make an incredibly sophisticated film about space aliens invading earth, and the super soldier that saved the planet? Yeah, that's possible. But for now, I feel safe saying "generally speaking, violent movies and games about a single hero slashing and shooting and killing his way to victory are almost universally pretty shallow and lacking in both theme and plot."

I actually would have stated all this before, Quickdraw, but it's such a complicated point, and my post was already so long, that I decided not to. Even if we disagree about Metal Gear Solid (and again, please note that I think the gameplay is spectacular), I hope we can agree that most games/movies/books/plays about a hero blasting or slicing his way to ultimate victory are very rarely any more than pure, juvenile fun. Which isn't inherently a bad thing -- it just isn't the experience I'm hoping games will bring in the future. 

I especially love when people title threads with things like "MGS4 on 360 CONFIRMED!!!" and then you open the thread and there is either 1) no link posted at all or 2) a link to a blog that said it heard from another blog that some guy said that MGS4 might not be exclusive anymore. Maybe. 

Even if I personally think a 360 port is likely (in my opinion, 6-12 months after the PS3 version), I think these frantic attempts to prove it's happening right now are a little absurd.  

Here's an example, Quickdraw, of a game I might say is approaching maturity, while still in the vein of Metal Gear Solid:

A spy is sent out to kill one person. And that's all he does: kill one person. In the entire game. That person doesn't even have super powers -- he's just a person. 

Have you ever read "Crime and Punishment" by Fyodor Dostoevsky? It's one of my favorites, and is generally accepted to be in the upper echelons of the western canon. The novel involves a student who murders a cruel and selfish pawn shop owner; he does this around 1/3 of the way through the novel. The rest of the book is spent inside his head, dealing with the psychological consequences of murder. That would be a violent game I could sink my teeth in to. 

@Bodhesatva, I see your point with the 1 vs 100 scenario... I'm hoping eventually for something closer to 1 char infiltrating, setting up resources(people working for you), over coming the enemy... like more clandestine spy work to come around... something like MGS: portable ops(PSP) but MUCH larger would be very cool. And remember that killing people is actually against protocol in newer MGS games, you rank better if you don't.

and hey, "love is a battlefield" LOL, your right it's corny, I think something is lost in translation.

Whew, thanks Vizunary. I am completely aware that I'm criticizing many people's favorite games, and in a pretty harsh way. I really am not trying to make enemies here: I just have very strong feelings about this, as you can see.

It's bed time for me. I apologize if I frustrated and/or insulted anyone, especially Ckmlb. I'm just personally hoping -- strongly hoping -- that games can evolve to a point where I can see myself playing them when I'm a mature adult. 10 years from now, 15, whatever. I personally believe the Wii is the first, painful step in that direction, as is evidenced by its first real and substantial penetration of the adult market in the last three decades of video gaming.

Final points: Props to Metal Gear. The gameplay is awesome. And please don't think that I believe everyone has to think like I do. If you don't care about games breaching the adult market, and are perfectly happy with the action-packed games that largely target 15-25 year olds, no problem. I'm just stating my personal preferences, that's all. Night, and <3 

In Chaos Theory you only get a 100% perfect score if (among other things) you don't kill anyone aside from three main NPCs. You can go and break everyone's necks if you are so inclined to do so, but the real challenge is completing all missions without so much touching anyone, let alone knocking someone out. Fantastic fun IMO.

@your mother... Hell yeah, this has always been my attraction to these types, it's usually not in your best interest to be a mass murderer.... though I am playing through a seperate save on Oblivion where I kill EVERY non essential char w/o getting caught, hehe, I can't help myself(replay value) ;)

and remember, "Assassins do it from behind."

Oh how I agree with you on the replayability bit, I do the same in Chaos Theory - the first playthrough is to suss out the level and kill pretty much everything in sight.

Once that's done, THEN I really go about being a spy. You get the best of both worlds - and yes, assassins do it from behind, but only because mercenaries won't take it up front...

 In Hitman Blood Money you can achieve a Silent Assassin rating only if:

1. No one sees you.
2. Only the target is killed
3. The target's death must look like an accident
4. No weapons or disguise is left behind