2 Responses to “Roundtable: Developing Mods as F/OSS”


It’s difficult to open source games. The main issue is creative control over the game:
- there’s one thing to allow other people to read your code, access your art assets etc.
- then there’s another thing to allow other people to commit code to your game, allow them to change art assets to your game.
With the second option, it is hard to get your idea of the game implemented: the community might chose to turn your envisioned zombie shooter into a 3rd person police investigation game.

id Software released the code of their engines AFTER finishing their products. And while they did release their whole code for idTech1, 2 and 3, it didn’t release the entire code of idTech 4. They released only the game code, meaning the parts of the code that would allow you to create game entities. No access to the low level stuff. From that point of view, idTech 4 is similar to Source SDK.

There’s also a big difference from releasing the CODE under GPL license and the ART ASSETS of the game. id NEVER GPL-ed their artwork. And from their perspective, of sharing the technology, they don’t need to.

The only fully GPL-ed game that I know of is Open Arena. It uses the Quake 3 engine (GPL-ed by id) and art assets released also released as open source (for compiled maps you also get the source version of it). But it also enforces some rules on what goes in the game and what not, maintaining some creative control this way.

Nice point on using the Source SDK and the EULA. Once you use the tools for any game, you agree to the EULA governing the SDK, and most of them do not let you commercially exploit them.
Distributing the mod as a ‘source’ package would indeed consist in selling third party assets (maps in Maya, models in 3DS etc) with a script that would compile them in game proprietary formats. That would normally be legal.
However, this would be:
- technically very challenging for the developers
- technically very challenging for the users. What if an error occurs during the ‘compilation’? As a user who just payed 20 USD for the mod, how would you feel?

Regarding copyright on game assets, with the guy making the maps for our mod, I wanted to use this kind of relationship:
- he owns the map. He is the copyright holder.
- he ‘licensed’ them to me to compile them for our mod.
And it turned out great! Further more, when we wanted to release the editable format of those maps, we asked for permission from him, and he was more than glad to allow us to share them.

@Tools for Open Source: those are actually tools for software development. Open source or not, developers ought to use a set of tools like that.

John, I didn’t know you were part of Mantis. Thumbs up!

@ Tools for Open Source: Not strictly for software development, but you’re right. Revised the title to read Development Tools Useful to Open Source Projects.

I think the original titles were based on the topics of discussion, but the new title still fits that context (william re-listened to get the titles and links, I just marked them up and added a few extra tools).