Client & Server Launch Options for SCP: Secret Laboratory

This page lists various launch options you can use when starting SCP: Secret Laboratory. These options can help improve performance, troubleshoot issues, or customize how the game runs. If you're using Steam, you can add them in the “Set Launch Options” section to change how the game behaves when it starts. (Scroll to the bottom for more detailed usage and examples.)

Make sure to include the - in the launch parameter as its required for the argument to be recognised. For example, use-force-d3d11 and not force-d3d11 as the latter will not work.

---

SCP:SL specific arguments

Argument	Description	Platform
-steam	Sets the platform to Steam.	Client only
-discord	Sets the platform to Discord.	Client only
-fdiscord	Forces Discord authentication.	Client only
-authdebug	Creates EnableDebug.txt in %appdata%, often used for verbose auth debugging.

Client only -noauth Forces the game to launch in offline mode. Client only -allow-syncbind Security Risk: Allows the server to log pressed keys (used in some mods or debug contexts). Client only -dnt Enables Do Not Track (DNT) mode. Client only -nosrv Disables DNS SRV record resolution.   -hidetag Hides the badge/tag above your name in-game. Client only -neverhidelocaltag Forces the local tag to always be visible. Client only -hidelocaltag Hides your local tag (even if shown by default). Client only -nevercover

Forces badges/tags not to be covered by the environment (debug/visual override).

Client only

--doh Enables DNS over HTTPS. Client only --http11 Forces HTTP/1.1 to be used. This will cause slow performance. Client only --http2 Forces HTTP/2 to be used. Client only --http3 Forces HTTP/3 to be used. Client only --tls12 Forces TLS 1.2 to be used. Client and Server --tls13 Forces TLS 1.3 to be used. Client and Server --ech Enables ECH for TLS 1.3, this is a security extension for TLS 1.3. Client only --ipv4 Forces IPv4 to be used. Client and Server --ipv6 Forces IPv6 to be used. Client and Server --weak-http-security Forces the game to use TLS 1.2 instead of 1.3. Client and Server --system-proxy Makes the game load with Windows proxy settings. May not work on other operating systems.
--early-data N/A
--nagle Enables
--unity-web-request
Client and Server

---

Unity engine arguments

These are the ones mostly needed for SCP:SL, For the complete Unity list, see the official docs: https://docs.unity3d.com/6000.1/Documentation/Manual/PlayerCommandLineArguments.html

Argument	Description
-force-d3d11	Force Direct3D 11. Useful for compatibility.
-force-d3d12	Force Direct3D 12.
-force-vulkan	Force Vulkan renderer. (This is experimental and mainly works well on linux/amd systems)
-monitor <N>	Launch on monitor number N (1-based).
-screen-width <px>	Set window width.
-screen-height <px>	Set window height.
-screen-fullscreen <0/1>	1 = fullscreen, 0 = windowed.
-window-mode <exclusive/borderless>	Choose fullscreen style (where supported).
-popupwindow	Borderless window (frameless).
-logfile <path>	Write player log to a custom path (use - for stdout).
-nolog	Disable player logging.

How to Use Launch Options

Client side:

You can enter these launch options in Steam by right-clicking the game → Properties → Launch Options.
Multiple options can be combined by separating them with spaces.

Here are a few practical examples:

Example 1: Game is crashing or showing a black screen

Try running in windowed mode and disabling fullscreen:

-screen-fullscreen 0 -popupwindow

Example 2: Steam is down or unstable launch the game using Discord

Sometimes Steam has issues or 3rd-party Steam servers go offline, making it impossible to play SCP:SL.
In such cases, you can force the game to use Discord authentication instead:

-fdiscord

Example 3: Running the game on a low-end system

Force DirectX 11 and lower graphics settings:

-force-d3d11 -screen-quality Fastest