So if you have a specific case in mind, check the licensing terms and if you have doubts, ask a lawyer. In this case, the developers have approval, in other cases a game engine may be open-sourced but the game assets may remain under a commercial license, other cases may be entirely different. This is a more general question, and the most appropriate answer to 'is is legal to.' questions is 'ask a lawyer'.

Is it legal to distribute a free open-source implementation/adaptation of a videogame? The Bethesda emails are quite lengthy and numerous so I'll link them rather than quote them:

We do not condone, nor are responsible, for other websites that show (in images or video) Morrowind running on an Android device. You can choose to follow the main storyline. Anything else, is fair game, such as displaying videos of OpenMW running the OpenMW-Template on Android on the blog. An epic, open-ended single-player RPG, Morrowind allows you to create and play any kind of character imaginable. Bethesda Softworks has asked us to not promote any images or videos of OpenMW running Morrowind on Android or other mobile platforms, and we agreed to comply with this request.

There was a misunderstanding as to what OpenMW is (a new game engine) and isn’t (a Morrowind port) that was cleared up. We had a long email conversation with Matt Grandstaff which can be read on the wiki. Does Bethesda Softworks approve of this project? Won’t you guys have legal problems?īethesda Softworks is well aware of OpenMW and has given us approval to continue working on it, so long as certain conditions are followed. The OpenMW project maintains a FAQ page at where the legality issue is dealt with.

Morrowind free legal