Free with a PlayStation Plus membership from 5th March will be Dead Nation: Apocalypse Edition on PS4, Tomb Raider and Brothers: A Tale of Two Sons on PS3, and PixelJunk Monsters and Smart As on Vita.
Dead Nation: Apocalypse Edition, made by Resogun developer Housemarque, is a top-down zombie shoot-'em-up. It has a full campaign playable in co-op or alone, and includes the Road to Devastation expansion, which has Arcade and Endless mode, the latter doing exactly what it suggests.
Dead Nation was enjoyable but not spectacular on PS3 four years ago. Resogun, on the other hand, was fab. Perhaps Dead Nation will have a bigger impact on PS4.
A sub to PlayStation Plus costs Ł5.49/€6.99 a month.
Thanks, PlayStation Blog.