Expedition Alpha, without the guesswork

The short answer

Expedition Alpha is a 1.0 mission. Finishing it rescues the Mycologist, the fifth playable employee. Until you finish it, she is not on the roster.

That is the whole loop: one mission, one rescue, one employee.

What the developers actually confirmed

Three pieces of evidence line up, and they are all first-party or near-first-party:

1. The 1.0 patch notes introduce the Mycologist as a member of the first expedition to New Atlas after the fungal outbreak.
2. The launch announcement adds the condition directly: But first, you'll have to rescue her in Expedition Alpha.
3. The achievement list names the mission and describes it in five words: Rescue the Mycologist.

A fourth signal is structural. The 100% checklist groups Expedition Alpha with the other late 1.0 objectives — X11-B, Floor 10 of Incursion, Threat Level 7 — rather than with the Early Access regions. That is the strongest available hint about when in your progression it is meant to sit.

How to prepare

Since the mission sits in the late 1.0 block, prepare the way you would for any end-of-progression mission:

• Bring people. 1.0 added a hard failure rule: if nobody reaches the Drop Pod, the mission fails. A squad makes extraction far more forgiving.
• Do not build around one exotic. If a run depends on a single upgrade dropping, it is not a plan.
• Set a threat level you can clear reliably. A failed run teaches you nothing about the mission.
• Keep your grids functional, not optimal. You can re-spec after you see what the mission actually asks for.

The boss fight, step by step

The mission ends in a rescue, and the rescue is gated behind a boss. GamerBlurb's walkthrough breaks it down:

1. Start Expedition Alpha from the mission select on the New Atlas map, then follow the objective marker in.
2. Reach the floating boss — a large pink body inside a darker shell, with several damageable sides.
3. Pick one side and commit. Spread your fire across the whole shell and you delay the only thing that matters.
4. Break that side to expose the bright pink core, then move all damage onto the core.
5. Do not leave when the boss dies. She descends and lands nearby; walk over until the Switch Employee prompt appears and interact. That interaction is the actual unlock.

What the fight throws at you, per the same guide: tracking pink projectiles, spikes that travel along the ground, explosive barrels dropped into the arena, plus Crawlers and Pixies adding pressure. The projectiles are the attack to respect most — keep sprinting and dashing laterally while holding sight of the side you are breaking. Clear the adds when they start interfering rather than letting the arena fill up.

What you get

The Mycologist — Sporelift, Fungal Skewer and the Infection passive — plus the achievement. The studio also confirmed she receives an Amalgamation-exclusive character upgrade, which makes the Amalgamation a reasonable target once she is unlocked.

If the mission is not showing up

Three checks, in order:

1. Confirm you are on 1.0. If the Expedition Alpha achievement is not in your achievement list at all, you are not on the 1.0 build.
2. Confirm you are not on a beta branch. Beta branches can lag the live content set.
3. Check the 2.0.1 notes. The first post-launch patch fixed several progression blockers — the relay-tower Fulfillment, the Saxito bag counter, and two achievement triggers. A mission that appears stuck may be a fixed bug rather than a missing prerequisite.

If all three are clean and the mission still is not visible, that is worth reporting rather than grinding. There is no documented prerequisite to grind for.