unreal is not "open source". "open source" has a specific meaning and Unreal doesn't fit. Some people call unreal "source available" https://www.google.com/sea

unreal is not "open source". "open source" has a specific meaning and Unreal doesn't fit. Some people call unreal "source available" https://www.google.com/search?q=open+source+definition https://www.google.com/search?q=open+source+definition