PlayStation 4 launch-day bundles are back in stock on Amazon, after the online retailer sold through all units earlier this month. The official Amazon Video Games Twitter account says the bundles are "guaranteed on release date," though Sony has yet to announce an official launch day for the PS4. PS4 Bundles available through Amazon include Battlefield 4 + PlayStation Plus ($500), Killzone: Shadow Fall + PlayStation Plus ($500), Knack ($460), and Watch Dogs ($460). A PlayStation Plus subscription is required to play PS4 titles online. Non-bundle PS4 launch editions remain sold out. By comparison, standard Xbox One units are available on Amazon, though all launch-day Xbox One systems are sold out through the retailer.