The game--only sold as a $9.99 digital download via the online PlayStation Store--is said to contain "plenty of modes to satisfy your trigger finger needs, including Arcade Mode, Planet Mode, Endless Mode, Bomber Mode and more."
While the listing makes it sound like the game contains all of those modes, it turns out that Endless and Bomber Modes are missing from the final product. An in-game statistics page also mentions a Survival Mode that is not present.
Those modes will return, says IGN, in a forthcoming expansion pack that "you'll have to pay extra for it." No release date or price has been provided for the expansion.