Can games made with stratagus be sold legally?
Link to a FAQ
Yes, provided you provide the source code when requested.
Stratagus has GPL v2 license, so your game must be under GPL v2 too, because it will use Stratagus code. I think that GPL license does not forbid selling game, but then you must distribute Stratagus and Game under GPL license. So you must provide GPL source code without any restrictions and license payments.
by providing 'source code', does that mean that only the stratagus engine source needs to be provided, or does that include graphics and everything else?
All game stuff which stratagus is using must be distributed under GPL v2. So graphics, music, scripts, helper programs, ... must be under GPL v2.
Thanks Pali, that solved my question.
I don't believe that is correct. The game stuff can be separately packaged and released under a seperate licence. Take Wargus for example, the graphics and music certainly aren't GPL v2.
what do you mean by 'separately packaged'?
I just meant that you need to make a clear distincation between your GPL stuff and your non-free stuff. Your art assets do not need to be GPLed if they don't derive from a GPL source (eg. completely original).
There are a few discussions of this around, such as: https://answers.launchpad.net/stratagus/+question/183043
Thanks Kyran Jackson, that solved my question.
Game scripts must be under GPL v2 for sure, because they using and calling GPL functions from Stratagus Engine. (So scripts are derived work of Stratagus).
Maps data for Stratagus are in Stratagus Map format (I do not know exact name), but this format is specific for Stratagus Engine, so maps should be in GPL v2.
Game data (sounds, graphics, maps) in Wargus are problematic. They come from original Warcraft II Game (which are not redistributable), created for Warcraft II. So they are not derived work of Stratagus, so no GPL license here... Next In Wargus we have (maybe problematic) GPL program which convert Warcraft II (PUD) maps into Stratagus format.
So if you create some game data for Stratagus, I think it must be under GPL v2 (as derived work). But if you create some music, graphics, maps for other project (maybe in other format?), they are not derived work of Stratagus and thus you do not have to distribute it under GPL. But then if you want to use it in Stratagus you should create some GPL tool for converting data to Stratagus format (like wartool in Wargus).
I'm not a lawyer and questions about GPL license are not easy. Maybe you should contact your lawyer before distributing parts of game under non-compatible GPL license.