STFO

Quick start

STFO requires BetterTerminal. r2modman and Thunderstore install that dependency automatically. Scripts are stored here:

BepInEx/config/STFO/Scripts

STFO creates the folder when the plugin loads. Add demo.stfo, then use:

SCRIPTS
STFO CHECK DEMO
RUN DEMO
LIST MEDIPACK | STFO DEMO | QUERY

Practice terminal

This browser simulator teaches command flow. It does not execute STFO code and cannot reproduce GTFO or IL2CPP behavior.

Language

@stfo 1
@program main
@pipeline process_items

FUNCTION main()
    name = INPUT("NAME:")
    PRINT "HELLO"
    PRINT name
    choice = OPTION("ACTION:", ["CONTINUE", "STOP"])
    OUTPUT choice
END

FUNCTION process_items(items)
    ordered = SORT(items, "ID")
    RETURN TAKE(ordered, 3)
END

Supported structure includes variables, functions, IF/ELSE, WHILE, FOR, lists, maps, imports, PRINT, OUTPUT, RETURN, input and options.

Configuration

File: BepInEx/config/STFO.cfg. Runtime commands:

STFO CONFIG
STFO CONFIG RELOAD
STFO CONFIG ENABLED ON|OFF
STFO CONFIG WRITES ON|OFF
STFO CONFIG STATS ON|OFF
STFO CONFIG UPPERCASEINPUT ON|OFF
STFO CONFIG INPUTLIMIT 1-65536
STFO CONFIG LISTLIMIT 1-1000
STFO CONFIG PROMPT TEXT
STFO CONFIG MARKER TEXT

File writes are disabled by default. Keep them disabled unless a reviewed script needs them.

Security and reliability limits

STFO is a bounded interpreter, not a proven security sandbox.

• Memory is estimated by the interpreter, not capped by the operating system.
• Execution time is checked cooperatively while VM instructions run.
• Writes are workspace-confined and reject links/reparse points, but implementation bugs remain possible.
• Private input means STFO avoids intentional terminal echo. It is not encrypted.
• Downloaded scripts remain untrusted content. Read them before execution.

Limits cover instructions, estimated memory, elapsed time, call depth, import depth, source size, collection size and string length. They reduce accidents; they cannot guarantee GTFO will never hang or crash.

Client and multiplayer behavior

Scripts run on the client with STFO installed. They are not automatically sent to or synchronized with other players. BetterTerminal works without STFO; STFO cannot load without BetterTerminal.

Verified and unverified

STFO 1.0.1 compiled without warnings or errors against BetterTerminal 1.1.1. Package layout and automated Thunderstore publication succeeded.

That does not verify every script, rundown, multiplayer setup, host migration, mod combination or long-running session. GTFO does not officially support mods and updates can change IL2CPP behavior.

Reporting problems

Include STFO, BetterTerminal and GTFO versions; script and command with private data removed; config; installed mods; reproduction steps; expected/actual behavior; and relevant BepInEx/LogOutput.log lines.

Open a GitHub issue · Source code

Development disclosure

STFO was developed with assistance from OpenAI Codex. AlexanderMakunin directed, reviewed, tested, packaged and publishes the project. AI assistance does not guarantee correctness.