OverviewL.A. Noire - one of the first games to feature this concept.
As DLC offerings for games have continued to increase, some publishers have begun selling a "season pass" that provides access to all (or a specific set) of the game's downloadable content, usually sold for a discount. Season Passes typically include DLC that is not immediately available upon a game's release.
Another variation of the Season Pass is seen with some episodic games, such as The Walking Dead and Kinect Sesame Street TV. These games offer individual "episodes" of the game for purchase, but also offer a Season Pass which bundles all the episodes together for a discounted price.
This business model was first seen in 2011, with L.A. Noire's "Rockstar Pass," which granted access to four new missions, two new outfits, and a "badge pursuit" challenge mode. The price for buying all of this content individually is $20, but the pass originally sold for $10 (a limited-time offer; the price was later raised to $12). Around that same time in 2011, Mortal Kombat also offered a season pass for it's downloadable fighters.
Some argue this business model provides benefits to both publishers and players alike. For publishers, this bundling together with a discount may influence players who were going to only buy a small amount of DLC to purchase more of it to take advantage of the discount. Additionally, by offering pre-orders of future DLC they can collect revenue before the DLC is officially released. For players, those who were already planning to buy all of a title's DLC are able to receive a somewhat significant discount.
Some have criticized that publishers can abuse the Season Pass by deceptively offering only a portion of the DLC, leaving out some content that must still be purchased separately.