Complex sentence: In 2008 it was announced that Vivendi Games and Activision were to form Activision Blizzard, a described by a former developer, the merger changed the mood of Radical and made it like a first-party developer, instead of indie.
Split into simpler sentences: In 2008 it was announced that Vivendi Games and Activision were to form Activision Blizzard. The merger changed the mood of Radical and made it more like a first-party developer, instead of indie.