ANSWER: No, they are not.

EXPLANATION:

Well, in most games, you are defending yourself from evil. In others, however, you are fighting for glory or whatever. This is merely fiction, it's not real. However, if you fear that this could affect you negatively, then I advise against playing them.

You have to remember: It's just a video game. A real life is not actually being taken. As long as there is no harm done in real life, it is okay to play.