This is Steam's 12th annual Winter Sale. Each year the event has drawn a ton of traffic to the store, with last year's sale attracting billions of page views for Steam's titles from users all around the globe.
This year's sale features an "Extremely Cozy Cottage of Surprises" theme, each day offering players the chance to open a new door and receive unique Steam Community emoticons, wallpapers and/or in-game items from community favorite Steam games -- as well as some consumable digital items of questionable utility from Valve.
Along with daily surprises and discounts on thousands of games, players can vote for their favorite games and studios of the year in the Steam Awards. The winning games and studios are targeted to be announced in early February 2019.
The 2018 Steam Winter Sale is on now and will end on January 3, 2019 at 10am PT.