First off: I think it's great you're considering an opensource license. The community can use such topclass work. But I do think you are not up to snuff on the intricacies of opensourcing. (which is very understandable, license-issues can be minefields). There are hundreds of licenses for starters, which can mean very different things, for end users and you the creaters. I read that you fear people 'stealing' the game. With viral licenses like the GPL this is impossible. The 'new' game would have to be GPL too, and then pointing out that they're just copycats would be easy. Then again, if they're effectivily just redistributing, whats the problem? One of the points about opensource is that these things should be possible. If you just don't want that, maybe it's just better to keep it closed after all. If people cant effectivily do anything with the code/art, then no use making it OS under some prohibitive license. About 'losing copyright'. Copyright is something that lies automatically with the original writers/artist. No action required on your part, ever. I know many people equate open source with GPL, but that of course nonsense. You could choose BSD, LGPL or as I said, hundreds other or your own custom license. I sincerely suggest contacting a legal advisor from (for example) the FSF (http://www.fsf.org/licensing). AFAIK they provide advice to developers for free for precisely these kinds of issues. Maybe others know of even more places to obtain advice (I'm not really into this either).