Gaynor Bell, who lost two children in violent deaths, said the project was created to try to turn children away from violence at a young age.
Despite the game's 18-rated status, she said many children would have played it, and similar games, at home with elder siblings, and that they risked being de-sensitised to the violence involved.
She added: "They are shown a picture of a man rolling over a car and you can clearly see it has a machine gun.
"It's basically telling them that it's not real life, but in these games they do look real."
She added: "Children have very short attention spans so they need something that keeps them interested, preferably busy with their hands and it has to be something that allows them to be proactive."
via news.bbc.co.uk