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I was wondering why don't developers of AAA games release their source codes after their game has sold out and support is long gone?

Of course there is this list, where you can find a lot of AAA games with available source code.

I just don't seem to understand why don't other companies do this with their old games? They certainly don't support it any more, and sales are negligible. I am not even sure, if releasing the source would negatively impact a games sells.

I am sure a lot of games, that are doomed by gamespy's closure, could be saved by the community, had their source codes been released.

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Legal issues with 3rd party libraries. Also, just because the game isn't selling anymore doesn't mean the code isn't still in use. –  Ben Apr 14 at 23:15
Not so sure this is specific to game development. This is general to all developers. –  Byte56 Apr 14 at 23:23
@Byte56 I think it is particularly relevant here as in many other areas of software it is not actually unusual for source to very old software to be released, I think the gaming middle-ware situation uniquely prevents this nearly completely with games. –  Vality Apr 15 at 10:05
Open sourcing code is not free. It takes time to maintain, deal with pull requests, and deal with the inevitable support emails that it generates. –  superluminary Apr 15 at 12:06
I think there are a lot of old games, that would benefit from going open source. Lots of old games still have players, and if the community could do their own patching, maybe some new players would buy the old game. –  VSZM Apr 15 at 19:23

4 Answers 4

up vote 54 down vote accepted

The short answer is because it's usually a legal minefield, and there's usually little or no return on the investment a company would need to put in to the effort.

The source code and assets of a game are intellectual property. It isn't always true that all of the source code and assets are the property of a single development studio. For example, the studio may have licensed source code to some engine and made modifications to that code.

That means that the studio would need to identify and remove any source code or assets they do not have the license to redistribute or re-release. Similarly, they would need to vet the entire code base for references to trade secrets or other concepts that they are still bound by legal agreements to keep secret or contained. They'd probably want to scrape the source code for potentially offensive comments or references that may reflect poorly on the company.

That's a lot of work for a non-trivial code base, and that's still only presuming the legal ownership of the code is clear. In many cases with these sorts of games, the original IP holder is out of business or otherwise dissolved, and then you have the mess of who owns what of the remnants of the studio. This can be an extremely complex legal mess depending on how the studio went under and what the initial incorporation agreements were.

Given that, in these contexts, the games in question are usually no longer popular, it's unlikely a studio (or the postmortem IP holder) would see any kind of return on the investment necessary to clean up and solve all the legal and other issues with the code. Failure to properly vet all the outstanding intellectual property legalities in a source code release could result in the IP holder of some violated property filing a lawsuit or taking other legal action against the company, as well.

Of course, all that being said, there's another quite common reason that's relatively orthogonal to the legal issues: they just don't want to. Maybe they don't care, maybe they are hoping to re-use some of the code later in a re-vitalization of the original game, et cetera. It's their IP, they can choose how to distribute it. Or whether to distribute it at all.

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"If that's not going to bring revenue - don't do it". On the other hand, even old games still sell on sites like GOG. –  Krom Stern Apr 15 at 4:20
That reminds me the story of Jedi Knight II and Jedi Knight:Jedi Academy, which were released on github then removed 2 days later because of patent issues on some components of the code. –  Lærne Apr 15 at 5:57
"maybe they are hoping to re-use some of the code later in a re-vitalization of the original game" or more likely already have, or have sold part of it to someone else... –  jwenting Apr 15 at 15:01
and then there's the associated artwork, which is an entirely different (but related) can of worms. And especially in old games the artwork is often encoded into the game binaries, so can't be easily extracted and removed from the source distribution archive. –  jwenting Apr 15 at 15:04
IP meaning intellectual property, right? –  Pierre Arlaud Apr 16 at 7:32

One aspect that hasn't been mentioned before regarding legal issues are software patents.

With a lot of crazy simple stuff out there that's patented, companies may be afraid of publishing the source code in case someone will find out that the game they made millions of has violated a couple hundred (frivolous) patents, and suddenly they're flooded with lawsuits.. which can be expensive even if you "win".

(As far as I know, this hasn't happened with released game source code so far, but I would be surprised if IP trolls weren't mining all the source code Microsoft has opened for various software patent violations..)

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Interesting aspect, thank you. –  VSZM Apr 15 at 8:02
Surely you mean, "IP trolls are valiantly promoting innovation by ensuring that there is a profitable industry devoted to purchasing and monetising inventors' rights to their inventions"? Didn't think so. –  user44630 Apr 15 at 14:58

On top of what Josh Petrie said, there's also the matter of getting something to work properly.

One such example that I can remember is when the source code for Penumbra was released. Big github repository made public for the Humble Bundle support. It had build notes and all the necessary libraries to build it. However it still took most people several days before they could get it to properly build.

You would be surprised just what a few years can do. APIs change for 3rd party libs, and many things are no longer valid documentation-wise. Angelscript was a big problem for Penumbra because the API changes between versions were huge.

The other big issue is that there's rarely any worth to publishing the source code to a big game. Especially if a company puts a fairly restrictive license on assets and the engine, this poses a big problem for the people interested in the code. This is to protect the works of the developers typically, but many open-source games like that will restrict anyone from making a commercial game off their old code.

So then the open-source game becomes a possible learning experience at best. I don't know about a lot of engines, but most of the open-source ones I've seen are not the best examples. They work because many people put thousands of hours into them. However many games and engines like that tend to be hack-ish, and made for a very specific purpose that tends to not be helpful for budding developers.

Even if someone got their hands on the Source engine source code for example, it wouldn't be terribly helpful if they wanted to apply that to their own project. They would simply be overwhelmed.

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While true, this is (and should not be) a barrier for releasing the source code. There have been open source projects to port old games over SDL that have taken months to run, but people have still put the effort into it to do so. –  Jari Komppa Apr 15 at 5:36
I 100% agree that it shouldn't, but it is a big decision that a number of studios will consider before puttingin the effort to make the release. –  Thebluefish Apr 15 at 15:13
I've actually offered to do the cleanup for free to several companies, with no takers (thanks to Remedy for letting me do the Death Rally port though =) –  Jari Komppa Apr 15 at 15:18

Let's say you create a huge successful game project that is complicated as far as game physics. It wouldn't be great for people to know how to make an exact copy of it, maybe even changing things and publishing it as theirs. First off there would be legal rights problems and copyright. Just like flappy bird, people make clones but don't use the exact name in the market.

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Game mechanics are not difficult to copy; game engines are. If the clone can afford to pay for the same or an equivalent game engine, closing source of the game won't protect much it. –  Lærne Apr 15 at 5:53
The question was specifically about games which do not return any revenue anymore. That means even when someone would create an exact copy, it would have no negative impact on the developer who made the original. –  Philipp Apr 16 at 13:26

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