# Staying safe

Fusion runs other programs and changes games, so it's worth knowing exactly what it does.

## What Fusion does to your games

- **It starts them for you**, the way their router says (usually through Steam), hidden behind
  Fusion's window.
- **Setup changes files only through a recipe with undo.** One-click setup writes down every file
  it adds or replaces; **Undo setup** in My Games puts them back. Close the game first.
- **It talks to a game through a small kit** inside the game (a mod, or Fusion's guest SDK). The
  kit only answers Fusion's questions on your own PC; nothing goes over the internet.
- **It never copies a game's files** out of the game, and never shares them. Share and publishing
  compare every file against your installed games and refuse a package that holds one.

## Your saves

A router may load a save of its own (The Long Dark's router plays a save named "Fusion", never
yours). Routers are new, so **back up your saves** before you try a game the first time.

## Signatures and tiers

Every update of Fusion and every hub package is signed. Fusion checks each signature itself:

| Tier | Who signed it | May contain |
|---|---|---|
| **Official** | SteonMod | anything |
| **Verified** | an author SteonMod checked | anything, after review |
| **Community** | its author | text, Lua, pictures, sounds, models: **no program files** |
| **Unsigned** | nobody | the same as community, with a stronger warning |

Lua in routers, addons and Devices runs in a sandbox with time and memory limits: it can't open
your files or the internet.

## Anti-cheat and online games

Fusion is for single-player games. It refuses to attach to a game whose anti-cheat is running, and
a game with anti-cheat only works through its own official offline mode. Never use Fusion online
against other players.

## What leaves your PC

- **Update checks**: Fusion asks steonmod.com for its release list (Settings → Updates).
- **Content hubs**: it reads their lists and downloads packages you install.
- **Compatibility reports**, only if you turn them on (Settings): the router, its version, the
  game's build, worked or broke, and Fusion's own words about what went wrong. No names, paths or
  files.

Nothing else. No account, no tracking.

## If something looks wrong

A router asking for something strange, a package Fusion warns about, a crash: tell us in the
[Help forum](https://steonmod.com/forum). If a router is harmful we take it down for everyone
through the signed feed.