No publisher is safe from E3 leaks, especially Ubisoft. Two of their rumored titles were in the Great Walmart Canada Leak of 2018™: an unnamed Assassin's Creed and Splinter Cell game. And while we don't know about Splinter Cell (yet), Ubisoft confirmed the existence of Assassin's Creed Odyssey today in a teaser tweet and trailer. Only a logo, two seconds of gameplay, and a "See you at E3" message were in the tweet.
It's hard to believe that Ubisoft wanted to reveal Odyssey like this via tweet today. A pretty convincing leak this morning came by way of an Assassin's Creed keychain and was later backed up and corroborated by Kotaku, who has broken Assassin's Creed reveals in the past multiple times in a row for multiple different games in the series. Faced with evidence, Ubisoft probably knew the cat was out of the bag and decided to prematurely unveil their grand E3 reveal.
As if the Spartan helmet from the logo and keychain was any indication of its setting, the vicious kick reminiscent of the movie 300 in the short trailer lends more credence to the game being set in Greece. But we don't know anything else about the title other than that it now officially exists. The other parts of the leak, such its supposed deeper RPG ties, dialogue trees, and two playable characters, are still unconfirmed. Ubisoft will more than likely squash or confirm these rumors during E3.
Showing Assassin's Creed Odyssey at E3 and having merchandise for it does make the rumored fall 2018 release seem more likely. Assassin's Creed Origins was shown at E3 2017 and released later that year. And while it did look like the franchise was taking a break after Origins, it no longer looks like that is the case. It looks like we have to wait until E3 for Ubisoft to spill more details on this already leaky game.