Alien Invasyndrome Demo Walkthrough

Adult Demo notice (brief)

Alien Invasyndrome (Steam 4603980) is an 18+ stealth-action Demo by Mozu Field / 百舌鳥, published by Shady Corner Games. You are a weak alien larva aboard Atlas. This walkthrough follows the Demo chapter flow seen in v0.99.1 gameplay: intro, nesting, skill tree, Kitchen, Security Way A / Way B, boss, Demo end. Tone stays mechanical. Wishlist the TBA full release on Steam.

Sibling depth: Kitchen Route, Security Routes, Walkthrough Hub. Systems: How to Play, How to Nest, How to Beat the Boss.

Alien Invasyndrome Demo v0.99.1 gameplay

Chapter 1 — Intro and larva basics

The opening sells Atlas as humanity’s exploration vessel and drops you in as a fragile alien larva. Treat the first minutes as a movement lab, not a rush to every door.

Goals:

1. Learn walk, interact, and hide without panic mashing.
2. Locate at least one reliable desk softlock near your starting corridor.
3. Confirm UI readability. If Japanese text is missing or tiny on non-JP Windows, pause and set Locale Emulator before blaming the Demo.
4. Internalize that detection is expensive — plan on about one minute under cover after a clear spotting. See Stealth and Detection and Detection Timer.

Do not sprint into Kitchen or Security Room during the intro. Finish the teaching loop, then bank nest progress.

Chapter 2 — Nesting

Nesting is the Demo’s real power curve. The larva stays weak until the colony loop starts converting risk into upgrades.

Priorities:

• Secure a nest footprint before sightseeing Clinic, Laboratory, or Cafeteria.
• Capture / interact only when patrol gaps exist; retreat to desk softlocks immediately after loud actions.
• Prefer short, repeatable nest trips over long sightseeing loops.
• Keep Nest Checklist open if you lose track of session goals.

Deep read: How to Nest. If you softlock under furniture and cannot leave, jump to Softlock Fixes — distinguish intended hide from a stuck state.

When nest income feels stable, open the skill tree. Skipping nest for early Security Room clears is the most common Demo wipe pattern.

Chapter 3 — Skill tree (INT / STR)

After nesting unlocks meaningful points, open the skill tree. Demo builds teach two broad axes:

• INT — control and utility leaning options that reduce brute confrontations.
• STR — pressure when stealth windows shrink and objects or threats need force.

Spend rules for a clean first clear:

1. Buy stealth / nesting support nodes before dumping everything into one axis.
2. Align early spends with the Security branch you expect — see Security Routes.
3. Use Skill Tree, Early Build, and Skill Planner if labels differ between patches.

Leave a few points unspent until you see Kitchen patrol density. Over-investing STR before you can softlock on command wastes the nest economy.

Chapter 4 — Kitchen

Kitchen is the mid-Demo pressure room: food-wing sight lines, doorway checks, and furniture that matters when you get spotted. Treat it as a timing puzzle.

Route habits:

• Scout from corridor shadow before entering the main floor.
• Commit interactions only after a patrol turns away.
• Softlock under desks when aggro spikes; wait the ~1 minute hide if fully spotted.
• Return nest progress after a successful Kitchen slice instead of chaining into Security Room half-dead.

Full room notes: Kitchen Route. Map context: Key Rooms and Atlas Overview. Inputs refresh: Stealth Actions.

Clinic, Laboratory, and Cafeteria may appear as adjacent risk or landmarks depending on your build path. Do not assume every Steam blurb room is mandatory for Demo end.

Chapter 5 — Security Room Way A and Way B

Security Room is the Demo’s mid-to-late gate. Gameplay chapters often show Way A and Way B as alternate approaches into the same security problem space. Learn both conceptually even if one run only finishes one branch.

Way A (Security)

Way A tends to reward disciplined stealth entries, desk resets, and patience at chokepoints. If your build leaned INT and softlock mastery, Way A usually feels cleaner. Failures look like leaving hide early and re-aggroing the same patrol chain.

Way B (Security)

Way B often shifts timing or approach relative to Way A — still stealth-first, but with different pressure windows. STR spends help when you must force a stuck patrol pattern, yet they do not replace hide discipline.

Before you commit:

1. Read Security Routes for branch detail.
2. Skim Security Room for guide-level framing.
3. Confirm nest and skill readiness; abort back to nest if detection is spiraling.

Chapter 6 — Boss

The Demo boss caps the Security arc. Enter only when:

• Nest economy is not starving.
• You can softlock on command without menu confusion.
• You understand the detection minute as a full reset, not a slap.
• You have a planned INT/STR mix for the pressure pattern you saw on your Security branch.

Fight checklist lives in How to Beat the Boss. If the encounter softlocks you under props, use Softlock Fixes after a calm exit — do not mash every key.

Boss play is still stealth-action DNA: wait for openings, punish, retreat. Treating it like a pure brawler undoes the nest investment you made earlier.

Chapter 7 — End of Demo

After the boss sequence, the Demo ends its vertical slice. Expect a stop point rather than full Top / Middle / Lower Atlas completion. Wishlist Steam, note which Security branch you cleared, and decide whether a second run should flip Way A ↔ Way B.

Post-Demo reading:

• Demo Review for a grounded take.
• Changelog and Steam Status for build drift.
• Walkthrough Hub to jump straight into Kitchen or Security siblings on a replay.

Session checklist (one clean Demo clear)

1. Locale / keyboard sanity — Keyboard, Locale Emulator.
2. Intro softlock practice until hide → wait → exit is automatic.
3. Nest before deep rooms — How to Nest.
4. Skill tree with a plan — Early Build.
5. Kitchen slice — Kitchen Route.
6. Security A or B with a pre-read — Security Routes.
7. Boss — How to Beat the Boss.
8. Wishlist Steam 4603980; stop while ahead if detection spirals.

Common wipe causes

• Leaving desk hide before the ~1 minute detection decay.
• Skipping nest for Laboratory or Cafeteria tourism.
• Dumping all points into STR while failing basic softlocks.
• Entering Security Room without reading A/B differences.
• Assuming full-release ship layout equals this Demo slice.

Keep this page as the spine. When a chapter blocks you, open the sibling route or guide linked above, then return here at the next heading.