Please be as specific as possible when letting us know what is missing or incorrect. For example, say "this game's trophy difficulty should be 8/10", with a link to a website corroborating this difficulty estimate (if possible), not "this game's trophy difficulty is wrong".
Platinum is an in-game currency that can be used to purchase weapon and armour skins, arrival emotes, banner customizations, and more. You can also use it to upgrade your Hunt Pass.