Call of Duty, Killzone and Mario through colour blind eyes

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Shooting teammates and mistaking foes for friends is par for the course for video gamer Dave Lee.

The BBC technology journalist is colour blind and unable to detect the difference between red and green.

The colours are used to identify players in some of the world's most popular games.

He has discovered that some developers are introducing options to help people with his condition, while other games leave him confused.

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