FAQ

Short answers. Each links to the page with the long one.

Can I sell a game made with Kerosene? Yes. The licence does not restrict commercial use. (Publishing)

Do I have to open-source my game? No. The Kerosene Exception lets you link the engine into a closed game. Your code, levels, assets and scripts are yours; the engine part stays GPL with its source available. (Licensing)

Isn’t the GPL viral? How can my game be closed? On its own it would be. The exception is an additional permission under GPL §7 that says a game linking Kerosene is not a covered work, on conditions: engine source, the built-with notice, an attribution screen, and — if you changed the engine — the whole modified engine published. (Licensing)

What do I have to ship alongside the game? Both texts (LICENSE, LICENSE-EXCEPTION) and a README.txt with the notices. kiln --ship writes all of it; you fill in where the engine source can be obtained. And the game itself shows an attribution screen at start. (Shipping checklist)

What is the attribution screen? “Built with Kerosene”, shown each time the game starts, before or with the first interactive screen. It can be brief and dismissable; it cannot be switched off. Draw it in Game::ui for now — the engine will draw it for you eventually. A game on a modified engine shows “built with Fork, modified from Kerosene”. (Publishing)

Can I remove the “Built with Kerosene” notice? No. It is a condition of the linking permission and a notice §7(b) of the GPL lets the project require. Remove it and the permission goes with it, which makes the whole game GPL. (Publishing)

Can I ship Chisel or the compilers with my game, for modders? Not inside the distribution kiln --ship makes, and not without also distributing their source: the tools are GPL binaries in their own right. Point modders at the Kerosene repository instead, or build your own mygame-tools on kerosene::tools, which ships like the game. (Publishing)

I changed the engine. What do I owe? The whole modified engine stays GPL with the exception; it says “modified from Kerosene” with the version you diverged from and a link back — in its notice, the game’s README.txt and the attribution screen; and if your game is closed, the modified engine’s complete source is published where anyone can get it. The project would rather have a pull request. (Publishing)

Can I make my own engine out of Kerosene and call it “Kerosene: Ultimate”? Yes, and the project would like that — the way Titanfall’s engine was a rewritten branch of Source. The name costs what a modified engine already owes plus publishing its whole source whether or not a closed game ships on it, and saying plainly it is a derivative rather than the official one. (Publishing)

Do I owe anything for Symphonia (the MP3/FLAC decoder)? No. Only Timbre, a build tool, links it, and kiln --ship never puts a tool in a distribution. The one MPL-2.0 dependency a game does carry is smartstring, and its notice is written for you. (Licensing)

Can I use Source or Hammer assets, or open a .vmf? No, on both counts. Kerosene’s formats are its own and deliberately cannot read theirs, and the project ships no Valve or id content. Bring your own. (Licensing)

Is it game-ready? Not yet. It is 1.0.0 alpha. Everything works end to end — make a game with kerosene-tools new, draw a level, compile it, walk around it, save and load — but main menus, gamepads, combat, networking and crash reporting do not exist yet. (Publishing)

How do I start? cargo install kerosene --features tools, kerosene-tools new mygame, cargo play. (Getting started)

Will an update break my game? Not without saying so. Kerosene’s version follows Semantic Versioning on the kerosene crate’s API: cargo update takes fixes and additions, and a breaking change waits for a major version, with the changelog saying what to change. The 1.0.0 alphas are the exception. (Versioning)

Does it run on Windows or macOS? CI runs every test on both, and makes and plays a new game on each. Nobody has played one there by hand yet. (Platforms)

Can players mod a shipped game? Yes, trivially: a loose file under content/ shadows the same path in the .vault. That is also why there is no tamper protection. (Publishing)

Can I make a game without writing Rust? Yes — a content-only project: maps, entity I/O and Rhai scripts on the stock runtime. The moment you need something the stock entity classes cannot do, you need a game crate. (Making a game)