In response to post #24687944. #24694624, #24722859, #24734084 are all replies on the same post. "Cryengine has one advantage, in that so long as you never charge for the game, you never pay either, unless you continue your subscription." I see the same in the FAQ for the Unreal Engine. Consider the restrictions they impose carefully. As this whole controversy over Skyrim mods shows, when the pool of value gets large enough, those who can will try to monetise it and they won't care about who or what gets trashed in the process. The only way to avoid this is set restrictions which prevent anyone from monetising the pool of value. There are ways to do this, but it needs to be done early to be effective or there will be constant fighting to gain advantage for future gain instead of constant creation of value.