Hmm skins wise I believe there's.
Nightfall= watch all the episodes of nightfall in one sitting.
MC IV/V (can't remember which) you get for buying Halo 5 I think
Helioskrill= you get after completing all 4 games campaigns on legendary.
And anyone that pre orders at GAME or GameStop in the US gets Lockes armour.
All of which is unlock able via REQ cards.
Only thing that's 100% not gettable is FOTUS armour/emblem which you only get via the console edition.
English
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The helmet for fotus looks weird =( I wish it would have been a different armor. I think only the emblem is exclusive though.