01
Checkpoint Guide
Run the document, clearance, clock, face, headcount, and daily-order checks in a repeatable sequence.
Read protocolIndependent Fan Guide · Launch Build Evidence
Trust the Manual. Verify Everything.
Security 51 guides built around the current checkpoint rules, official systems, and clearly labeled player observations—without invented endings or fake certainty.
- Released Aug 12, 2026
- 68 Steam Achievements
- Windows & macOS
- Choices · Horror · Simulation
Official facts first Current-build checks Unknowns stay unknown
First Verified Batch
Five Focused Protocol Files
Each guide answers one distinct player intent. Ending conditions and achievement requirements remain deferred until the full-release evidence is reliable enough to publish.
02
Anomalies
Separate document mismatches, visible tells, photo anomalies, scans, and elevator threats without memorizing yesterday's rule.
Read protocol03
Medical Tests
Use certificates, fingerprints, blood samples, the microscope, and blood type results at the correct point in the stack.
Read protocol04
Quarantine
Know when the current bulletin supports deny, security response, isolation, extermination, or continued observation.
Read protocol05
Walkthrough
Follow the launch-build progression from Level 1 through blood analysis and the Day 30 branching timeline unlock.
Read protocolAbout the Game
What is Security 51?
Security 51 is an atmospheric horror checkpoint simulator developed and published by Alawar. You screen staff in an underground Area 51 facility, verify access, watch the elevator, and decide who may enter, who must be stopped, and which threat cannot be allowed back outside.
The launch build layers documents, clearance, time, headcount, photographs, body and organ scans, fingerprints, blood analysis, quarantine, infection control, field operations, and delayed consequences. Daily instructions can override the default workflow, so these guides teach a verification stack instead of one permanent answer table.
Open the WalkthroughDeveloperAlawar
PublisherAlawar
ReleaseAugust 12, 2026
PlatformsWindows · macOS
ModeSingle-player
Procedure Before Instinct
Start the Next Shift Prepared
Begin with the checkpoint sequence, then open the specialist protocol that matches the tool or decision causing trouble.