# Your first fusion

This page walks you from the Library to playing, in about five minutes.

## Finding your way

Fusion looks like a game store's library. Along the top are four tabs:

- **LIBRARY** (Fusion opens here): everything you can play. The list on the left has your
  **Experiences** (finished games made from the games you own) and **Sandbox** scenarios (open
  worlds to play around in). Click one to open its page, then press the green **PLAY**.
  **Home** shows a short guide, the Experiences, what you played lately, and everything as covers.
- **CONTENT**: get more, always free: routers for other games, Experiences, scenarios and addons.
- **CREATE**: make your own scenarios with cards (no code), or fix a game's router in Router
  Studio.
- **MY GAMES**: the games on your PC and what Fusion can do with each.

**SETTINGS** is on the right. The arrows at the top left go back and forward, like a browser.

On an item's page:

- **PLAY** starts it. Next to it: which of your games it uses ("You own 1 of 2 games"), when you
  last played it, and how much memory it needs.
- **+ Add to stack** plays several things together. **Your stack** (bottom right) lists them;
  drag them into order, then **Play the stack**. The top one brings the world, who you play and
  the ending.
- **Remix** (Experiences) or **Edit** (sandbox scenarios) opens its cards so you can change it.
- **Share** saves it as one file for a friend.

## Play something that needs no game

Start with a scenario that says **No games needed**, such as the **Playground** or the **Cube**.
They use Fusion's own test game, so they always work.

1. Press **Play** on it.
2. A small panel shows each game starting. Fusion starts the games a scenario needs by itself:
   you don't open them first.
3. You're in. Walk around. **Esc** frees the mouse; press it again to go back to the Library.

## Controls

| Key | What it does |
|---|---|
| **W A S D**, mouse | move, look |
| **Space** / **Shift** | jump / run |
| **E** | use a screen in the world (and step back from it) |
| **Q** (hold) | the spawn menu (in plain scenarios: [The sandbox](https://steonmod.com/docs/sandbox)) |
| **C** | the context menu: click anything, from any game, to change it |
| **1 2 3 4** | tools: Grab, Spawner, Remover, Weld |
| **V** | fly (noclip) |
| **F5** | Devices: place timers, triggers, score counters ([Devices](https://steonmod.com/docs/devices)) |
| **F6** | the cost meter: how much each game uses |
| **F7 / F8** | see the shared collision / every creature and prop Fusion knows |
| **F9** | measure performance (start, then stop) |
| **Esc** | free the mouse; again: back to the Library |

An Experience can turn some of these off: it decides what you may do.

## Play with one of your games

1. Open **My Games**. Fusion lists the games it found on your PC and what each needs.
2. A game that says **Needs setup** gets one-click setup: Fusion installs what it needs into the
   game, keeping a list so **Undo setup** puts it back exactly as it was.
3. A game that says **Not supported yet** has no router on your PC. If the content hub has one,
   you'll see **Community routers (N)**: press it and **Install**.
4. Back in the **Library**, scenarios that use that game are now playable.

> [!WARNING]
> Back up your saves before trying a game for the first time. Fusion plays its own save where a
> router supports that, but routers are new and made by people like you.

## When something doesn't start

Fusion keeps running even if a game doesn't. It says what went wrong in plain words ("VEIN
stopped", "close the game first"). [Fixing problems](https://steonmod.com/docs/troubleshooting) lists the common ones.