If you only want people not to sell it GPL (I recommend v2 by the way) is enough since people are obliged to offer any changes in source code back to the community as a new GPL project. You can also write you own license saying something like "the source code distributed herein is only intended for execution and compilation of the game, any changes or redistribution via unofficial means is not permitted and thus liable to damage to the full extent of the law".
Though lets be honest here, both ways:
1. The license is just a virtual piece of paper. If anyone wants to use your source for things you're not allowing they will. You're probably as an individual not in a position you'll be able to acquire lawyers and threaten possibly international lawsuits unless there's major money involved, which is a super unlikely scenario.
2. That is exactly the same argument why you should go ahead and do it if you're not too worried about your game's code. There are tons of open-source code out there and it's only like once in a decade your hear about misappropriation, and that's usually a very small piece of code like kernel code (with the exception of
the VMWare incident...). People are usually very respectful of the devs wishes, for one reason or another - especially since there's not much to gain by disrespecting a license either way. What's the absolute worst can happen? Someone taking you game code and turning it into a commercial product? What are the odds of that happening since it never happened before - not to mention there's not even a decent niche market for commercial roguelikes....
I guess this is why most roguelike devs release their source code as open-source anyways, I know I do. Anyway if you ever plan on making that come true count me in to get the build process working on Linux (or helping with a custom license text). I'm not an expert in either of the areas but hopefully good enough - it would be the least I could do in exchange of enjoying your game
