Complex sentence: A scriptwriter from outside the company was hired to write the game's cutscenes; numerous script rewrites were needed, as the cutscenes "often would be reacting to the mission or setting up what happened next".
Split into simpler sentences: A scriptwriter from outside the company was hired to write the game's cutscenes. Numerous script rewrites were needed, as the cutscenes "often would be reacting to the mission or setting up what happened next".