I thought, "Why not Hive since we have a gaming background?"
I'll first point out that this isn't an accurate statement by itself. Most people here probably play or have played Warcraft 3. This isn't a very violent video game at all. It's too cartoonish, bright, unrealistic themes and the bird's eye perspective cuts out a lot of violence. Don't get me wrong, I'm sure there are plenty of people here who have played worse games, but my point is that your asking a community who probably has less overall experience in more violent video games. You need to draw opinions from more gaming sites than just the Hive workshop.
Do violent video games affect people in a bad way?
There is no simple and short way to answer this.
The way a game can change somebody is through emotional attachment. Whether it makes us feel greedy and rewards us for it, makes it appear normal to swear, makes bad morale's look cool, showing jealousy and a negative way to deal with it, etc. Games can scare us with dark atmospheres, show blood, all in which can be traumatic. Go ask a physiatrist of how certain aspects of kids lives are affected by traumatic events.
I think children are the most vulnerable to being influenced by games. Grand Theft Auto teaches children the swear words before they may be ready to hear them and use them properly. It shows children that swear words are a frequent common part of everyday life. Children don't know any better so they may just take after the game.
Some games have disturbing images which may confuse children. Take Zelda A Majora's Mask for example. Despite a PG rating, many reviews have made claims about some themes, symbolism, etc in conjunction with strange contrasts and imagery. which points to elements such as death, sadness, grieving, etc. This confusion could lead to all sorts of things.
There are some very violent video games. Seeing blood, especially in great quantities, can be traumatic for children. Frequent use of bleeding, dismemberment and other gore and be showing children the wrong thing. Seeing too much of something that isn't suppose to be seen can send the wrong message. As adults, we teach out children that hitting is wrong. Imagine what some games depicting people sawing off arms and things are showing kids? Kind of the opposite of what mummy is saying.
In conclusion, I don't think mid aged teens and older are susceptible to being negatively influenced by games or if they are, it would be mild. I believe kids are because they are innocent, children copy people in order to learn. They observe, brain chemicals are different. They wouldn't understand the wrong of something if they weren't shown the right first, etc.
I think the only case of older people being affected by video games is if they have some kind of mental disorder or are on some kind of drugs which may corrupt their judgement to some extent.
Worry not, a game will not turn you into a serial killer or a freakin' bully.
This is talking about a serious case of how a game can affect you. Its the argument that everybody (media interviewing the cliché ignorant stay at home American mother) brings up and its plain wrong. Despite video game possibly affecting children (in my opinion as explained above), it would not drive them to such extremes. If anything, its not the game, but a case of mental illness, bad parenting or some other serious factors and cannot be blamed on a mere game.