Most of this applies to redistributing others' works (modifying them and using them for yourself need not apply to this discussion). Perhaps you found yourself an old mod that you liked, probably during Enraged Koala or whatever older version. And of course, it doesn't work, so you modify it so that it works on Glad Giraffe. And this hypothetical mod of course was beloved by most everyone but was left alone because it doesn't work. Would you agree that it's ethical to re-release the mod, given... The original creator is in the credits, and should probably fill your entire credit page The original creator cannot be contacted (probably doesn't log on the forums and never left an email or website or anything else). The mod was not modified in any way extraneous from the edits required to make it compatible.