The original StarCraft single-player campaign contains 30 missions.
Those missions are divided among three episodes, one for each playable faction: Terran, Zerg, and Protoss. Each episode contains 10 missions, creating a structured narrative that shifts perspective as the conflict develops.
The Terran episode introduces the Koprulu Sector’s political and military crisis. The Zerg episode follows the Swarm’s expansion and the rise of Kerrigan, while the Protoss episode centers on the defense of Aiur and the response to the Zerg invasion.
The count refers to the original game’s main campaign rather than Brood War. The expansion adds three further faction campaigns with additional missions, so counting the full original-era story requires keeping the base game and expansion separate.