I'm a developer and have messed with Homebrew games. With freemium being the future of gaining clearly who wants to remake destiny PvP as another fantasy scope based fps with supers double jump etc.. we the people can do what bungie can not. We can still discuss different game engines and different methods to do it since it's it's own game but thinking unreal engine would be the easiest approach for a free game that can be edited and updated w ease later.