Sign in to follow this  
raccoonone

Open Source licenses in commerical games?

Recommended Posts

I'm going to start working on my own multiplayer game fairly soon, and plan to make it as cross-platform as possible. To that end I plan to write it in C# (using Tao and Mono) or in Python (using wxPython and PyOpenGl). I know next to nothing about legal licenses though. Could someone explain a few things to me, or point me to a website which discusses license issues? I know that with GPL software I would need to release the source code if I use any libraries that are GPL. 1) I believe I can use libraries released under the MIT (X11) license, the BSD license, or the LGPL and not have to release my source code, is that right? 2) If I use libraries released under the X11 license, users would have the right to freely re-distribute my game (even without my consent), is that correct? I don't really expect to make any money off this game, but I'd like to know what my options are (and what options I might be eliminating) when I choose which framework to use. Thanks for any help.

Share this post


Link to post
Share on other sites
Thanks, I didn't think about the possibility of copyrighting the rest of the content.

I didn't really understand the second part of your post though. Do you mean that all of those 'free' licenses will force me to release my software under their license?

Share this post


Link to post
Share on other sites
Quote:

I didn't really understand the second part of your post though. Do you mean that all of those 'free' licenses will force me to release my software under their license?

I believe he is referring to licenses such as the GPL which stipulate that you 'free' you source code (that is, make it available in one of a specific set of forms).

Share this post


Link to post
Share on other sites
Quote:
Original post by jpetrie
The GPL is suitable to use in a commercial application. But so are those others.

I personally prefer the MIT or BSD license.


Wouldn't using the GPL for a commercial application mean that the users could redistribute it freely--which would kind of defeat the purpose of selling your game in the first place?

Share this post


Link to post
Share on other sites
Yes and No.

The GPL stipulates that if someone has access to the binary, then they must also have access to the source. That they are free to modify that source, AND they must share their modifications with you.

So, if you license the game's code under the GPL, then you can sell the game to someone, and if they ask, you have to give them the source. I do not believe that the GPL requires that you provide the source to people who have not bought the game.

I may be wrong about it though, and it is, arguably, the most important point.

Share this post


Link to post
Share on other sites
I think you're right. But that would mean that if one person bought my game, they could request the source code and then give it away for free, or even resell it themselves. I might decide to open source my game, in which case that would be fine. But I'd like the option of selling my game for a profit, in which case GPL would not work well I don't think. So I'm wondering if licenses like X11, would put me in the same situation where I wouldn't really be able to sell the game for a profit.

Share this post


Link to post
Share on other sites
Quote:
Original post by raccoonone
Wouldn't using the GPL for a commercial application mean that the users could redistribute it freely--which would kind of defeat the purpose of selling your game in the first place?


Not quite, although it might seem that way [smile]

Let's say you GPL the source code of your project. That means that users are allowed to have access to it (since you are making it open source in the first place). Users can modify the source and in turn they have to also release those changes; that's how the license works. So you make a game, GPL it's source code, and sell the game. What prevents people from being able to do the same?

Game assets. You are distributing the source code for your game for others to learn from and possibly some of the assets. The game's assets, artwork, music, etc... are not GPL'ed themselves. They belong to you, or whomever the copyright you licensed them from. Users would not be able to legally redistribute these resources, so they would essentially have to come up with their own assets to actually make their own version of your game and sell it.

There are many games that have done this, Quake being one of the main ones. A classic game, Warzone 2100 did similar, but was nice enough to include most of the game assets. In fact, here is their readme from that package:
Quote:

Warzone 2100 Source & Data

1) These source and data files are provided as is with no guarantees.

2) No assistance or support will be offered or given.

3) Everything you will require to make a build of the game should be here. If it isn't, you'll have to improvise(*).

4) None of us here at Pivotal Games are in a position to be able to offer any help with making this work.

5) This source code is released under the terms of the GNU Public License.
Please be sure to read the entirety of this license but the summary is that you're free to do what you want
with the source subject to making the full source code freely available in the event of the distribution
of new binaries.

Finally, the primary motivation for this release is for entertainment and educational purposes. On the subject of the
latter, don't be surprised to see some pretty gnarly old-school C code in here; the game was a classic but
large areas of the code aren't pretty; OO design and C++ evangelists beware! We haven't spent any time
cleaning the code or making if pretty - what you see is what you're getting, warts n' all.

Thankyou to Jonathan Kemp of Eidos Europe for permitting the release. Thanks also to Frank Lamboy for
assistance with the release and for campaigning along with many many others over the years for the source to be made
available. The correspondence, online petitions and persistence made this possible. We were constantly amazed at the
community support for Warzone even after all this time; it's nice to be able to give something back,
assuming you can get it to compile...;-)

6th December 2004
Alex M - ex Pumpkin Studios (Eidos)

(*) Except FMV and music...


Microsoft also did similar with Mech Commander 2.

So, it's possible to GPL your code and still sell your game. However, you will need to ask yourself if it will be worth the trouble hounding the people who do violate the GPL and do try to take advantage of your setup. Good luck!

(All available open source licenses)

Share this post


Link to post
Share on other sites
I thought I answered this all in my first reply. [lol]

Doom SOURCE is GPL. DOOM assets, trademark etc, belong to ID. You can't give someone DOOM, just the source code, and the demo. You also can't make an official DOOM release, just a code port, or your own game.

GPL gives you some freedoms, and restricts others. Not a bad thing or a good thing. It's just not the license for everyone. Don't use it if you don't like it. Or you feel it's not relevant to your project.

Share this post


Link to post
Share on other sites
Something else to consider:
If you develop in Python, its easy to get the Source-Code (see the news of EveOnline this year :D), even if you "compile" it. So, you give the "code" to the users anyway.
I really suggest what others already said:
Copyright your Content like Textures, Objects etc.
Free your Source. It might have positive impact like getting fixes or help.
regards

Share this post


Link to post
Share on other sites
Note that, of course, you hold the copyright to both your code and assets the moment you create them. It isn't a special action you need to take -- although you can take such an action to register the copyrighted work with the US government (if you don't live in the US, something similar probably applies in your country).

Share this post


Link to post
Share on other sites
Quote:
Original post by Symphonic
Yes and No.

The GPL stipulates that if someone has access to the binary, then they must also have access to the source. That they are free to modify that source, AND they must share their modifications with you.

So, if you license the game's code under the GPL, then you can sell the game to someone, and if they ask, you have to give them the source. I do not believe that the GPL requires that you provide the source to people who have not bought the game.

I may be wrong about it though, and it is, arguably, the most important point.


That isn't quite correct, they don't have to share their modifications with you

They only need to provide source to people they distribute/sell binaries to, if their software is comercial you won't necessarily get the code unless you pay them even though their code is based on yours.

Personally i would avoid GPL libraries in a comercial game since its easy enough to find good LGPL, BSD or similarly licenced librares, But its definitly not impossible to make the code "free" while keeping the content proprietary (IIRC quake3 and most other old ID games have GPL licenced code these days but you still need to pay for the models, levels, etc (Except those that are included in the demo , but those are still not free to distribute as you please)

There is also the issue of licence compatibility since the GPL is viral. If you use a GPL licenced library all your code has to be released under the GPL, this means that if you use one GPL licenced library all other libraries have to have GPL compatible licences. (The GPL makes a few exceptions for "system libraries" , which includes DirectX, Win32, OpenGL, language runtimes, etc).

Projects like OpenArena is basically taking the code from quake3 and adding free models, sounds, textures and levels to make a completely "free" game, you might want to think about how similar projects could affect you. (How long would it take the community to create enough free content to create a competing product using the GPL licenced code ? How would that impact sales ?)

It should be noted that ID released their code under the GPL when the games were a few years old and no longer making alot of money, releasing it under the GPL immediatly would probably have had a different effect (It would most definitly have resulted in a game like OpenArena showing up alot sooner which could have had a negative impact on sales)

Also , people who say "copyright your content" are a bit misleading, everything you create is protected by copyright automatically (Even if you release it under the GPL or another "free" licence).

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this