Mission: Countdown

Mission: Countdown Alpha, Mission: Countdown Bravo, and Mission: Countdown Charlie are repeatable main quests in Fallout 76 that trigger the launching of an intercontinental ballistic missile to a map location selected by the player character.

Quick walkthrough

 * Enter the missile silo at ether Site Alpha, Site Bravo or Site Charlie.
 * Make a biometric ID card to bypass the security grids.
 * Fight through the missile silo to reach the control room.
 * End the lockdown by repairing the reactor.
 * Replace the mainframe cores (15 total).
 * Prepare the launch and defend the security chiefs while doing so.
 * Input the launch code and choose a target to complete the quest.

Detailed walkthrough
Before starting this quest, the player character will need to acquire at least one nuclear keycard and the decrypted weekly launch code for a silo bunker.

Upon entering a silo bunker (either Site Alpha, Site Bravo, or Site Charlie), be prepared for many robot enemies. Bring energy-resistant gear and energy weapons. A highly radioactive room will also be within the silo.

Once the quest is completed, the player character will be prompted to select a blast zone target location within Appalachia for the nuclear missile. Some lower-level areas located in the western portion of Appalachia are considered to be within a "protected zone" and cannot be targeted. If fissure site Prime is targeted, the scorchbeast queen will be spawned and the Scorched Earth quest will begin. Targeting other locations will spawn higher level versions of whatever enemy is normally present in that area.