http://www.thinkgeek.com/blog/2017/11/n7-day-a-celebration-of-mass-e.html

Maybe you’ve been hanging out in a frozen cave on Gellix for the last few years and haven’t heard, but N7 Day is a celebration of all things Mass Effect. BioWare celebrated the first N7 Day on November 7, 2012 to commemorate the fifth anniversary of the original Mass Effect game. Since then, BioWare and fans have celebrated the anniversary each year with fan art, cosplay, restrospectives, and amazing loot!