9. Gang Warfare
Since San Andreas, Gang Warfare has became one of the most exciting side missions to ever grace the GTA series. Simply put, these particular missions are considered to be GTA's equivalent to Horde Mode, where players and their supporting gang of NPCs have to mow down waves of rival gangs to lease them of their deed over the land. Players could take territories or defend them, and the latter would occur randomly, forcing players to stay on their toes.