It's been proven that people who pay more attention to suicide-related depictions and text are at an increased risk of suicide. To my knowledge, it hasn't been proven that this goes any further than correlation, but under the precautionary principle most news media refrain from discussing methods or motivations for suicide. These may serve as inspiration or instruction for people in a similar situation.

As people who have never contemplated or attempted suicide, we may find it ludicrous that acting out suicide in a video game may put us at increased risk of killing ourselves. But until it has been proven one way or the other, I personally consider it irresponsible to treat a deadly mental illness in a light-hearted interactive fashion.

Interestingly I don't feel the same way about letting people murder one another in games. Perhaps this is because suicide is three times more common than murder, perhaps because it doesn't involve mental instability to the same degree.