Assassin’s Creed: Origins

Assassin’s Creed: Origins is an action game developed and published by Ubisoft on October 27, 2017 for the Sony Playstation 4 and Microsoft Xbox One and PC platforms.

All the content initially available through promotions and Packs that can be bought from the in-game online shop were later made available in-game in Heka Chests, but some specific items doesn't show up for some players, so they are listed for completeness.

Some gear can only be obtained by taking part in the online events called The Trials of the Gods.

The game can be linked to the player's Ubisoft Club account and, by completing challenges and obtaining points, rewards can be unlocked.

Gear Packs

 * Predator Pack (previously known as Twitch Prime Pack) was released on October 27, 2017 as a timed exclusive until January 1, 2018 for Twitch Prime members. On January 23, 2018, the weapons and mount were made obtainable through the Nomad's Bazaar, while Aguilar's outfit was made available through Ubisoft Club (see above).
 * Mercenary Pack was an Amazon exclusive pre-order bonus for the PlayStation 4 and Xbox One physical Limited Edition in UK, France, Italy, and Spain. On December 5, 2017, the pack’s content was released through the Helix Store for 150 helix credits per item.
 * Tribal Pack was a retailer exclusive pack available by pre-ordering the game at Game UK, Verkkokauppa or by purchasing the Apple of Eden edition at JB-Hifi. On December 5, 2017, the pack’s contents was released through the Helix Store for 150 helix credits per weapon/shield and 300 helix credits for the mount.
 * Monster Energy promotion allowed to redeem codes found on Monster cans at Monster website for a chance to win in-game resources, drachmae or gear from the Monster Energy pool.
 * All the other packs were available from the Helix Store from the start for 1000 helix credits.

Bonus mission
On December 19th, 2017 a new mission called "A Gift from the Gods" was added as a cross over collaboration with Final Fantasy XV.

This mission featured a puzze that when solved gave access to a cutscene featuring characters from the Square Enix game and 3 pieces of gear: the Ultima Blade sword, the Ziedrich shield and a mount called Kweh.

This mission was taken out of the game on December 19th, 2018 to be re-added a few months later, in late March/early April 2019. It's not known if it will be removed again, given how the Final Fantasy XV counterpart of the cross-over (the Assassin's Festival) was only available once and it's said to be "difficult" to be brought back because of copyright.