Honestly it's kinda hard to make anything truly "original" these days. Everything new is going to have some elements that make it seem "unoriginal". Destiny is a first person shooter, so you can say it is copying Call of Duty, Battlefield, or even Doom. Also you can say because it has aliens and it takes place in space, it copies Star Wars or Star Trek. Halo has those same elements, so technically you can say it is "unoriginal". But you need to know those elements don't make the game. It's the story, the characters, the experience. If those can make you feel like you've done something new, then you have something "original".