Update 3: It looks like this is the final teaser we're getting for the new Mass Effect game today. The final clip shows the character's helmet and some sort of well-insulated N7 jacket. You can see all the teasers stitched together in the video below:
Update 2: Another Mass Effect teaser video, titled Defiance, has been revealed. You can see it below, but it appears to continue from the end of the original Epsilon clip, and shows that the mysterious character we're following wears N7 colors. The next teaser page, titled Post-Nebula, currently features a countdown that will presumably lead to another video reveal.
Update: After the Epsilon teaser, fans quickly discovered a link to another countdown under the name "Oculon-2819-Defiance" on EA's official site. Oculon-2819-Defiance is listed as an access code here, the same as Epsilon, so it's now looking pretty unlikely that either of these terms will be the official title of Mass Effect 5. It does, however, appear that we'll be seeing several more teasers in this vein throughout the day.
Original story: BioWare's N7 Day celebrations mostly seem to be about celebrating the existing games in the series, but the studio did have one teaser apparently aimed straight at the hearts of fans eager for more information about Mass Effect 5: "Epsilon."
"The team is ta1king their time to cr1aft a whole new adventu0re for you to enj1oy, with new stories, chara0cters, and experiences to fill it," BioWare wrote in its blog post. "At the end of t0he day, that’s w1hat N7 Day is about. Cel0ebr1ati1ng yo0u an1d th1is speci0al fr0anchise that br0ings us all to1get1her. W0e hope you’1ve enjoyed the glimpse1s int1o the fut1ure of the fra0nchis1e so f1ar. An0d don’t wor1ry, ther1e’s mo1re to come, but fa0rther away!"
Your eyes do not deceive you - there are indeed a lot of 1s and 0s in that text, and throughout the entire blog post. Fans pretty quickly strung them all together and ran them through a binary translator to find the word "Epsilon."
Fans have also discovered a countdown timer linked to that Epsilon term on the official EA website, which eventually refreshed to link to the video below. Yes, that's five seconds of somebody's boots walking toward... something. The page also includes references to an "Andromeda distress signal," seemingly hinting at the new game's ties to Mass Effect: Andromeda.
So what does Epsilon mean for Mass Effect? Well, that remains to be seen. Perhaps it's a single word subtitle for the upcoming game, in the vein of BioWare names like Mass Effect: Andromeda and Dragon Age: Dreadwolf. Epsilon is the fifth letter of the Greek alphabet, so it would make sense as the name of the fifth entry in the series.
There's another bit of trivia here. In the book BioWare: Stories and Secrets from 25 Years of Game Development, a number of working titles for the Mass Effect series were revealed. One of the options was, simply, The Epsilon Effect. If Mass Effect: Epsilon is indeed the name of the next game, that would be quite a throwback.
BioWare has repeatedly noted that the new Mass Effect game is still in pre-production, and insider reports have suggested that Dragon Age: Dreadwolf's delays have been pushing ME5 back, too.