A man whose son died after playing video games for long periods is campaigning for greater awareness of the risk posed by their excessive use. Chris Staniforth, 20, who would play his console for up to 12 hours, died in May from deep vein thrombosis (DVT). His father David believes the condition may have been triggered by long gaming sessions. DVT can form during long periods of immobility and can kill if the clots travel to the lungs. Computer records showed his son would sometimes play online on his Xbox for periods up to 12 hours.