Complex sentence: PewDiePie's commentaries had a positive effect on sales of indie games, such as McPixel "; developers of the game stated," The largest force driving attention to McPixel at that time were' Let's Play' videos.
Split into simpler sentences: PewDiePie's commentaries have had a positive effect on sales of indie games. For instance the developers of McPixel "stated," The largest force driving attention to "McPixel" at that time were' Let's Play' videos.