This Security 51 walkthrough is a progression map, not a visitor-by-visitor script. The retained launch-build source explicitly says visitors are randomized, so names, order, exact earnings, mistakes, and some encounters can differ. What remains useful is the sequence of major tools, facility systems, and decision habits from Day 1 through the Day 30 branching-timeline unlock.
Current launch-build routeSpoiler warning: this page names major threat phases, tools, facility systems, and the Day 30 progression event. It does not publish unverified ending conditions.
Before every shift
Use the same preparation routine even as the rules change:
- Read the entire instruction sheet while the game is paused.
- Identify the default deny conditions.
- Mark any condition that requires calling security.
- Mark any “let through regardless” override.
- Note the scan, certificate, photograph, UV mark, test, or blood result required today.
- Check the city and ward interfaces when they are available.
- Buy only the food, sanity items, and tool upgrades the next shift can justify.
The Checkpoint Guide contains the reusable desk order. This walkthrough focuses on what changes.
Progression at a glance
| Day | Major observed unlock or change | Main learning goal |
|---|---|---|
| 1 | Document tutorial and elevator basics | Compare identity fields and use approve or deny |
| 2 | Shift clock and body X-ray | Balance accuracy with time |
| 4 | Instant-photo tool | Wait for a developed image |
| 5 | Medical certificates | Separate genuine evidence from forgery rules |
| 6 | Elevator inspection and Isolation Ward | Inspect returning riders and contain threats |
| 7 | City monitoring and organ imaging | Split desk work from strategic operations |
| 9 | Thermal scanner | Distinguish cold and hot findings |
| 10 | Handbook emphasis | Match named anomalies rather than guessing |
| 11 | Bone imaging | Check location-specific skeleton rules |
| 15 | Level 2 and UV light | Inspect hidden marks on papers |
| 21 | Blood sample analysis and microscope | Collect, identify, print, and match results |
| 25 | Level 3 and response test | Add answer-based screening to the stack |
| 29 | Blood type testing | Resolve type, microscopic, and photo overrides |
| 30 | Branching timeline unlock | Move from linear shifts into outcome investigation |
Days 1–5: learn the desk
Day 1 teaches the minimum checkpoint loop: compare the two identity documents, match the face to the portrait, stamp the access decision, and operate the elevator after the first group. Use this day to learn where every document lands on the desk.
Day 2 introduces the real shift clock and the body scanner. Accuracy affects pay, but speed comes from a consistent scan order. Do not reach for the body tool before the name, numbers, and portrait have been compared.
Day 3 demonstrates why final actions matter. A specific mismatch or body-region finding can require security rather than ordinary denial. Read the action verb, not just the anomaly.
Day 4 adds the photographic tool. Let the image develop fully and move toward the strongest visual interference. Do not decide from the unfinished static.
Day 5 adds medical-certificate handling after a body finding. A certificate can itself be forged, and the current rule may treat forgery more seriously than the underlying anomaly. See Medical Tests for the evidence hierarchy.
Days 6–10: the facility opens up
Day 6 expands the job beyond the person standing at the desk. You can inspect people returning in the elevator, use camera modes, select a rider with a finding, and send the threat to the Isolation Ward when the tutorial allows it. The ward then introduces research.
Day 7 adds the city monitoring interface and organ imaging. This is the point where a clean desk shift can still fail strategically if the wider threat is ignored. Check the city layer, choose an available operation, then return to the queue.
Day 8 combines the desk, returning elevator, ward, research, and field-operation loops in one longer shift. Finish one interface before mentally switching to the next; most errors here are lost context rather than difficult rules.
Day 9 adds thermal evidence. Treat hotter and colder areas as separate named results. One can be a security trigger while the other is a protected override.
Day 10 puts more emphasis on the handbook and a named photo anomaly. Use the handbook while the game is paused, then compare the developed photograph to the named reference rather than reacting to generic static.
Days 11–14: combine deeper scans
Day 11 adds bone imaging and another certificate interaction. The daily rule can distinguish a bone finding from a forged certificate, so identify both before choosing an action.
Day 12 combines organ and bone evidence and demonstrates location specificity: a rule for one part of the skeleton does not necessarily apply to every bone anomaly.
Day 13 simplifies the tool mix but lengthens the queue. This is a good shift for practicing the document-first rhythm and clearing one visitor completely before starting the next.
Day 14 closes Level 1 with multiple scan categories active. Use a fixed order—documents, required organ view, required bone view, then temperature only when an override needs it. Random tool hopping wastes more time than a careful linear pass.
Days 15–20: Level 2 and hidden evidence
Day 15 promotes the player to Level 2 and introduces UV inspection of papers. Hidden marks can point to opposite actions, so inspect the exact symbol and match the wording.
Days 16 and 17 combine familiar photo, bone, and UV evidence with new named findings. The reusable lesson is to test only after a discrepancy gives that tool a purpose.
Day 18 focuses on specific internal-organ conditions. Check the named organs rather than sweeping every tool.
Day 19 temporarily removes normal ward access during a containment problem. Build your plan around the facility state shown today; do not rely on yesterday's isolation menu.
Day 20 restores ward activity and returns to a mix of body, bone, and exception evidence. When a default failure can be overridden by one scan result, run the override test before denying.
Days 21–24: blood analysis
Day 21 introduces blood sample analysis. Keep the visitor's documents visible, collect the sample, inspect it under the microscope, and print the named result. The observed rules distinguish between different microscopic findings, so “abnormal blood” is not enough.
Day 22 returns to UV and photo evidence. Use the break from blood tools to reinforce the rule hierarchy.
Day 23 focuses on internal organs with a specific exception. Check the named organ and exception material before deciding.
Day 24 returns to the microscope with a new pair of named results. Slow down during the sample step; this is where a hurried printout can be attached to the wrong mental record.
Days 25–30: Level 3 and the branching timeline
Day 25 promotes the player to Level 3 and introduces an answer-based response test. The observed threat phase changes, but the core process stays the same: verify identity, run the required test, identify the exact answer category, then apply the named action.
Day 26 expands the response-test categories and again includes a stronger allow exception. Read every category before judging the answer.
Day 27 is comparatively lighter and uses familiar UV and temperature exceptions. Use it to stabilize your resource position before the final complex shifts.
Day 28 combines organ, body, and response-test evidence. The retained walkthrough notes a possible inconsistency in one observed visitor; treat that as a dated player observation, not a universal rule. If your build disagrees, follow the current patch and report.
Day 29 adds blood type testing alongside microscopic and photographic results. Use a deliberate sequence and keep type separate from the named microscopic finding.
Day 30 combines the mature tool stack. After the shift, the observed route transitions into a story event and unlocks the branching timeline or shift map. The new interface allows the player to revisit or manipulate outcomes while investigating the current threat.
This page stops there. The retained evidence does not yet support a reliable post-Day-30 ending matrix, and publishing guessed branches would violate the site's evidence policy.
Spending and upgrades
The launch-build walkthrough reports different food, sanity items, and speed or scan-area upgrades across its run, but those purchases are not a universal optimal build. Earnings and mistakes vary with randomized visitors.
Use this priority instead:
- Prevent satiety or sanity failure.
- Buy the upgrade that reduces the next known tool bottleneck.
- Prefer scanning area when finding the target is slow.
- Prefer printing or processing speed when the result wait is the bottleneck.
- Keep a resource buffer before a new level or multi-tool shift.
Recovery when a shift goes wrong
- Reopen the instructions and identify the exact missed clause.
- Decide whether the error was evidence gathering or the final action.
- Restore the document-first sequence on the next visitor.
- Check the ward and city layers before ending the day.
- Do not restart solely to reproduce another player's earnings.
- If the rule appears inconsistent, preserve the day, branch, build, and screenshot before reporting it.
FAQ
Are visitors fixed by day?
No. The retained launch-build walkthrough explicitly says visitors are randomized, so use its tool progression and rule categories rather than expecting the same queue.
When does blood analysis unlock?
The observed launch route introduces microscope-based blood sample analysis on Day 21 and blood type testing on Day 29.
When does the branching timeline unlock?
In the observed route, it unlocks after the Day 30 shift and its following story event.
Why is there no endings section?
The full release was too new for the retained sources to establish exact, reproducible ending conditions. This site defers that page instead of guessing.
Should I copy the listed purchases exactly?
No. Visitor order, earnings, mistakes, and needs vary. Protect core resources and upgrade the tool that limits your current workflow.