Not to be a party pooper but have you tried to ask Bungie if you can make a copy of their game.
While you may use a different game engine and want to only do part of the game but Bungie owns all the proprietary and intellectual property covering Destiny and D2.
Even if your game was free to play any content like Destiny means you are walking into a lot of legal trouble.
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Only thing destiny can do is if I copied things they've sent in as copyright. I can't remake their super but I can rip off something for the example like just cause and make his hookshot a feature in a different game. Some of us aren't so narrow minded as yourself here.
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I'm not making Titans and hunters if you read I was remaking a fps fantasy scope based game. Didn't hear overwatch ask bungie nor did Tom Clancy ask call of duty for permission vise versa. I know copy right laws and honestly if I wanted to not make my own version as stated but a duplicate parody is protected as a legal form to even pirate things to edit as many have shown in court. I though wanted my own game that has a better management system.