Hello all! And please forgive any cryptic nature that might be found in my topic title.

I'm developing a 2D/sprite-based game engine which I wish to license to other independent developers for a nominal fee. Beyond talking to a lawyer about the specifics, I'm wondering if you guys could give me some insight into the more immediate questions. I'm building my engine on the shoulders of some 2D giants, e.g., SDL. I'm also using zlib. I've read their licenses, and I understand when I release my engine to a developer (header files, dlls, documentation) I must also include a copy of the LGPL agreement and of course SDL and zlib dlls, libraries and header files, or at least the LGPL and links/resources the developer can use to obtain their own copy of the SDL and zlib development files themselves.

I'm wondering am I allowed to license this engine at all, as it is built upon SDL and zlib? Must I simply include the required license and accreditation, or is my new engine also bound by the LGPL? Will games made by my engine be required to be released non-commercially? I've read on SDL's list of games webpage that Amnesia: The Dark Descent was built with some code from SDL, so I do believe there is some merit in thinking commercial games are possible with SDL.

I'm exploring these questions now much after development, since development is almost complete.

Any links or resources alongside some good old fashioned responses would be enormously helpful. I always fear some reprisal from asking seeming "obvious" questions, but I knew gamedev would be the best place to get some straight answers without spending too much time.

Yes, you can sell it. The licences mean exactly what they say - for redistribution, you must include the licences and the ability to get the source code for the libraries and make it possible for the end user to compile their own versions if they wish. There are no restrictions on sale. Commerciality or non-commerciality don't come into it.

The point of LGPL is that it only applies to the specific library, as long as it is dynamically linked with your code. That is the difference between that and the GPL, which would apply to your code if you wished to redistribute it, however it was linked or used. Even then, you're still allowed to sell it. There's just little point since people are legally entitled to copy it.

Ahh great, thank you for the reply. I've read as well that simply sharing the link to the SDL website would suffice, the place where other developers can get the source code to SDL.

(iOS, consoles and other restricted platforms are out of the question with v3 of both LGPL and GPL and that pretty much kills those licenses not just for AAA studios but also for a fairly large portion of the indie developers

What was the change in v3 that made this become a problem? I remember there being an outcry at the time the new licence came out, but I don't remember the details.

The fact you mention LGPL means you're probably using SDL 1.2, because SDL2 switched to zlib. Just remarking. You can still try to see if you can get an exception though, I know several SDL 1.2 games on iOS got an exception so they weren't bound to the LGPL.

If I was a much greater programmer, I most likely would be using SDL2, but since it's still deep in development, I decided the solid 1.2 foundation for an engine was the way to go.

Thank you all for the insights, I definitely feel more confident with my intentions, but to dig a little deeper: Selling/licensing a game engine built on software which uses these LGPL and zlib licenses is where I'd find the real hurdles? Now that I've written it out, it seems to make a good deal of sense to me... Why should I benefit financially from the work of a set of lower-level software? Creating a game engine designed to be sold for others to develop with is going to be a big no no here?