I've been developing a game engine for the past few years and I'm finally at a point where I want to allow people to make contributions and play with it and stuff. I want to put it up on GitHub, I'm just afraid of the rather unlikely event where my work gets stolen or copyrighted or patented or basically any kind of horrid legal thing that could happen.

I basically want some kind of license agreement that states:
- The engine source belongs to me, any contributions made to the engine by users are *non-exclusively* a part of that.

- Code added to the engine by a contributor is just a part of the engine and the contributor can still use that code outside of the engine freely still.

(EX: someone writes an awesome shadow calculation and puts it in the engine, they can still use that same shadow calculation elsewhere and it's fine)

- The engine is free to use non-profit

- The engine requires a lincse to use commerically which can be negotiated with me.

How should I go about that? I'm broke and I can't really hire a lawyer to write some crazy legal stuff for me.

I've read up on GPL and BSD but neither of those are quite what I want to do.

IANAL (I am not a laywer)

First, all code/art/music/whatever you create is automaticly copyrighted. If someone steals it, all you have to do is prove that you posted it online before they did (simplification. All you have to do is prove to a court that you created it). The GitHub page makes it public, and records the date.

Second, licensing is you basically saying, "I have these rights, but I'm willing to share some of the rights with you, if you follow certain conditions..."

Licensing doesn't have to be open to everyone, it can be just specific people. Additionally, you can license the code with one set of conditions to one group of people, and a completely different set of conditions to a different group of people.

This means, to satisfy your goals, you can (and should) have a different license for commercial vs non-commercial use.

BSD wouldn't be good (to meet your personal goals), because it basically says that anyone can use it even for commercial work.

LGPL also wouldn't be good for the same reasons.

GPL is a better option for non-commercial work, but even GPL allows commercial usage. The thing with GPL, however, is it forces anyone using it to release their source code of their project under the GPL as well, and most commercial software doesn't want to use it for that reason.

You could just have a plain-english agreement for the non-commercial version, and then negotiate for the commercial licensing. It'd have less legal strength then a lawyer-written agreement, but it'll still have a decent amount of strength.

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That said... What is the likelihood that you'll actually make any money licensing your engine? Does it offer features that Unity or the open-source Torque don't have? How does it distinguish itself against the hundreds of competitors? If the answer is, "It doesn't", then you should consider just making the entire thing LGPL.

LGPL means that if someone modifies the engine, they have to share the modifications. LGPL means, yes, they can use it for commercial games... but if you aren't going to make any money from licensing, then why not let people get real use out of it? I fully get you wanting to profit off your hard labor (as do we all!), but if the choice is that either they won't use it, or they'll use it for free, then I would suggest letting them use it for free.

My suggestion is, if you yourself don't think you'll make much money on it, offer it fully for free, even for commercial works.

If you do think your engine stands apart from the crowd, then yes, license the commercial version. But if it really stands out, then you'll really want to hire a real lawyer as soon as possible.

If you don't think that you'll make enough money to cover the lawyer's fees, then it probably isn't worth it to try to charge for it. But this is my opinion. You know your work, you know it's potential compared to engines like CrystalSpace and Panda3D, and you know whether it's worth the effort involved in trying to sell it.

Even if you commercially license it, and someone steals it, you'll have to pay for a lawyer to sue them anyway.

Thanks for the very in depth reply sir.

As for what you said... My engine does not stand up to stuff like CryEngine or UnrealEngine. It might be on par with Torque or Unity when I hit my goal but I'm still a ways off. I'm at the point where everything is implemented but not everything is finished. There are at least 150 //TODO: 's in the code and countless stubs and unoptimized stuff I need to improve.

The reason I want to put it up for public use is to have people look at stuff I've written and say "This would work better" or have people commit changes. And even have people put stuff in the engine and show me what's possible and what isn't so I can improve things as a whole.

In short, I just want to protect my work. GPL might be fine for now but it may not be in the future.

I doubt anyone at the moment is interested in licensing my engine but in the future it's a possibility. Their are a few things that set it apart. Multiplayer is integrated into the overall design so it's ready to go without having to re-code things or code around it. Mod support is built-in so that it's very simple to do and allows user made content to be added easily. And the engine is java based so it's native to Win/Lin/Mac.

I post dev vidoes here. http://www.youtube.com/user/dmtinfernocide

Sounds cool. There might be a market for a good multiplayer-focused engine.

What'll you'll need is a public license available for anyone to use, that specifies non-commercial use.
You might even want to make it permit commercial use for projects that make less than X amount ($25,000 or something).
You'll also need the license to cover modifications being folded back into the code.

If you can't hire a lawyer, plain-english is supposedly better than pretend-lawyer-talk. Though they are discussing contracts in that case, and I'm making the unfounded assumption that the same applies to licenses.

Sounds cool. There might be a market for a good multiplayer-focused engine.

What'll you'll need is a public license available for anyone to use, that specifies non-commercial use.
You might even want to make it permit commercial use for projects that make less than X amount ($25,000 or something).
You'll also need the license to cover modifications being folded back into the code.

If you can't hire a lawyer, plain-english is supposedly better than pretend-lawyer-talk. Though they are discussing contracts in that case, and I'm making the unfounded assumption that the same applies to licenses.

Alright, now I just need someone to point me in the direction of trusty resource on how to write a simple license agreement and how to apply it to my code bases and I can get on that tomorrow.