Telltale released a statement explaining the reason that the game is no longer available for sale.
Poker Night 2 has been withdrawn from sale on digital platforms due to the expiration of our digital distribution agreement. We currently do not have any plans to renew this agreement.If you already purchased the game, you can still redownload it from the platform on which you bought it. Telltale has posted a support article explaining the process.
This doesn't affect Telltale's other poker games, as Telltale Texas Hold'em and Poker Night at the Inventory remain available for sale.