Well this is pretty big news. The Metal Gear Solid V prequel chapter that came out last year, Ground Zeroes is going to be free next month for PlayStation Plus users. This will be available only on the PlayStation 4 platform, so sorry if you were holding out on a PlayStation 3 version.
Skulls of Shogun: Bone-A-Fide edition is also available and while I've never dabbled with it, I heard very good things about the title. Here are the other titles rounding out the PlayStation Plus game list for June.
Metal Gear Solid V: Ground Zeroes (PlayStation 4)
Skulls of the Shogun: Bone-A-Fide Edition (PlayStation 4)
Super Exploding Zoo (PS Vita, PlayStation 4)
Futuridium EP Deluxe (PS Vita, PlayStation 4)
Call of Juarez: Gunslinger (PlayStation 3)
Cloudberry Kingdom (PlayStation 3)
We can call that a pretty solid month in my book. make sure you have at them when they go live in June.