Factorio Forums

As Factorio is nearing (at least in the coming years) its development end-of-life, will Wube go down the route mod-friendly games like Minecraft once pledged but never truly delivered on (until very recently), namely, to sublicense and release the source for the core game engine (making up the "factorio.exe" binary), as strictly opposed to its commercially-licensed EULA-bound assets (under "\data", including the "core" and "base" mods that make up all of the lua scripting, definitions, textures, sounds, and so on), the same way id Software has historically done with the Doom and Quake engines?

This would greatly expand its life expectancy at no apparent cost (beyond maybe some internal cleaning-up of the code-base), delegate the fixing of bugs Wube has deemed unfixable, or otherwise minor (about 70 forum-pages worth as of today), along with allowing the further development of the modding API beyond that which fell under the requirements of the original game (and might otherwise currently rely on lua scripting hacks due to hard-coding). Also decouple and maintain its dependencies (currently statically linked, probably in-tree), for example port to SDL 3.0, make it truly portable to support more platforms, CPU architectures, or even graphic APIs, etc.

This can be achieved using either a copyleft, permissive, or strictly non-commercial license (also known as source available licensing agreements), specifically to anyone that has already brough a license to the game, or even simply made non-redistributable (only individually available to licensed players). In which case, just as today "Space Age" is essentially a paid mod to the base game, under this scheme the base game would simply become a paid mod for the game engine.

If not, or if this topic has already been brough up or discussed before, an official response or clarification would otherwise be greatly appreciated.

As far as I know for example EA released their CnC source code without assets

This is a little more complicated than it might seem.

Depending on how the Switch version was designed, they may have to remove all proprietary Nintendo Switch-specific code before releasing anything. That could be a much bigger lift than simply cleaning up a few internal things.

For assets, there are licenses that allow copying and distribution while disallowing modified versions of those assets from being distributed. That is similar to what the original Benchy 3D printing model did, partly because it had their website URL embedded on the bottom of the model.

They could also modify an existing license to disallow precompiled binaries. That way, the source code could be shared alongside the assets, but anyone who wanted to combine everything into a playable build would have to compile it themselves. That adds enough friction that most people would probably still just buy the game. Aseprite does something similar.

There are a lot of ways to handle this. It really depends on what the developers are comfortable with. Personally, I like the idea of eventually going the Quake route once they are done with the game, or doing something closer to what Valve did with the Source engine.

JustATempest wrote: Wed Jun 17, 2026 2:02 pm they may have to remove all proprietary Nintendo Switch-specific code before releasing anything.

Any potential Nintendo licensed code will only be in the switch version, so this will not be an obstacle to open sourcing the engine.

JustATempest wrote: Wed Jun 17, 2026 2:02 pm Depending on how the Switch version was designed, they may have to remove all proprietary Nintendo Switch-specific code before releasing anything. That could be a much bigger lift than simply cleaning up a few internal things.

This would only concern the PC (at least Windows, Linux, and macOS) version of the engine, since as far as I know it's the only platform that has historically allowed running and distributing arbitrary, or otherwise unsigned software outside of a preexisting licensing agreement. As far as I can tell from the attributions listed in "licenses.txt", Wube only makes use of permissively licensed software, for example SDL or lua (see also Technologies used).

JustATempest wrote: Wed Jun 17, 2026 2:02 pm For assets, there are licenses that allow copying and distribution while disallowing modified versions of those assets from being distributed. That is similar to what the original Benchy 3D printing model did, partly because it had their website URL embedded on the bottom of the model.

Allowing the redistribution of assets is pointless as far as my stated purposes are concerned.

JustATempest wrote: Wed Jun 17, 2026 2:02 pm They could also modify an existing license to disallow precompiled binaries. That way, the source code could be shared alongside the assets, but anyone who wanted to combine everything into a playable build would have to compile it themselves. That adds enough friction that most people would probably still just buy the game. Aseprite does something similar.

See, my point is, the game assets as of now are already fully non-obfuscated, and the game has no DRM to speak of, which is why I'm arguing that licensing the engine in a similar state of accessibility would have no practical effect on illegal redistribution, since the "factorio.exe" binary by itself is pointless, anyone inclined to pirate the game would not even bother with the engine source in the first place.

• If the source is non-redistributable, only community patches would be made publicly available.

• If it is privately redistributable (for example a modified community-version strictly gated between licensed players), and/or under a non-commercial license, but you wanted to make and sell a game based on the engine, you would still have to license a commercial license from Wube, while a free game from scratch would probably be fine with due attribution, like any overhaul mod currently available to licensed players on the portal.

• If it is publicly redistributable (simplest solution), say under permissive or copyleft license (latter of which also enables paid dual-licensing for use in proprietary games which is what id Software has done with the GPL), you would still need to pay for access to the base game if you actually wanted to play Factorio or any of the mods based off it (like Space Age).

You could also see slightly more elaborate setups where "engine.dll" would be separated from "factorio.exe", and be made available to modify and compile by yourself under "\source", the same way the API is currently documented under "\doc-html".

You may find this interview with kovarex to be interesting as it comes “directly from the developers”. According to the translated transcription:

2:39 For example you are thinking about making Factorio open source. Can you tell us more about that?
2:45 -Yes, I can. -Philosophically... I wanted that for a long time.
2:52 It's great for communicating with our programmers. Others can have a look at how we did it.
2:57 The people can give us feedback, tell us how to make things better.
3:02 They can be inspired to create something. They can work for 5 years to make a game based on Factorio but modified beyond recognition.
3:14 Why not? As a programmer, I'd appreciate the possibility to analyze the source code of other games.
3:22 There are reasons why not to do it but it seems to me that in a year or two, after the DLC is published and things quiet down,
3:36 let it be open source. That's quite interesting philosophy.

Various bits and pieces of the C code have been published already, such as the train path finding algorithm.

Good Luck!

eugenekay wrote: Wed Jun 17, 2026 11:43 pm You may find this interview with kovarex to be interesting as it comes “directly from the developers”.

Thanks, I knew I heard about this idea from somewhere before. That sounds exactly like either a permissive, or dual-licensed commercial/non-commercial scheme.

eugenekay wrote: Wed Jun 17, 2026 11:43 pm Various bits and pieces of the C code have been published already, such as the train path finding algorithm.

Right, the game also ships with a fully-loaded pdb which hints at the architecture of most of the code already, but the point would be to make available, as open-source guidelines would say, "The source code for a work [which] means the preferred form of the work for making modifications to it."

Actually, I re-read the EULA and realized that infamous clause applying to mods could similarly apply to engine modifications, making the source EULA-bound, where all modifications would automatically become licensed to Wube to its sole benefit, remaining the only party allowed to distribute compiled versions or some-such. That would be a far cry from most open-source standards, but at least you could still be allowed to improve the game, essentially as an unpaid volonteer.

See also how Unreal Engine is licensed, and technically source-available.