Poster for Call of Duty: Modern Warfare 3 l
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Call of Duty: Modern Warfare 3 launch

Modern Warfare 3, which went on sale at midnight on Monday, is expected to be the biggest video game of all time.

However, the game almost did not happen, after dozens of the staff resigned last year in protest at the sacking of the firms co-founder by parent company Activision.

Mark Rubin, executive producer at Infinity Ward, spoke to BBC's Daniel Emery about the challenges of developing Modern Warfare 3.