The PlayStation Plus Instant Game Collection expands by a single game this week, and it's a quality one: PixelJunk Monsters Ultimate HD for the PlayStation Vita will be free for all Plus members beginning tomorrow, April 22.

　　PixelJunk Monsters Ultimate HD was released on Vita and PC last year and is an enhanced version of the PlayStation 3 tower defense game PixelJunk Monsters, which was originally released in 2007. Ultimate HD consists of all the content seen in the original game, as well as everything from its Encore expansion pack and the Deluxe version of the game released on the PlayStation Portable.

　　In addition to the new free game, PlayStation Plus subscribers will also be entitled to some small discounts on a handful of digital games for PS3, PS4, and Vita. Those includes deals on two new releases--Octodad: Dadliest Catch and Cel Damage HD--both of which arrive on the PlayStation Store tomorrow.

　　The full list of deals follows below:

　　Batman: Arkham Asylum - $12.59 (regular price: $13.99)Batman: Arkham Origins (PS3) - $25.19 (regular price $27.99)Batman: Arkham Origins Blackgate (Vita) - $12.59 (regular price: $13.99)Cel Damage HD (PS4/PS3/Vita) - $8.99 (regular price: $9.99)Injustice: Gods Among Us Ultimate Edition (PS4/PS3) - $25.19 (regular price: $27.99)Injustice: Gods Among Us Ultimate Edition (Vita) - $12.59 (regular price: $13.99)Lego Batman 2: DC Super Heroes (PS3/Vita) - $12.59 (regular price: $13.99)Mortal Kombat vs. DC Universe - $12.59 (regular price: $13.99)Octodad: Dadliest Catch - $11.99 (regular price: $14.99)All of these deals will be available for one week; along with Monster Hunter Freedom Unite, which is currently free for Plus members to download on Vita, the sale prices will be going away on April 29.