That’s right, today we’ve learned that the PlayStation Now service will have 650 games available to stream during June 2018. This month 12 great games are on offer including, Sniper Elite 3 Ultimate Edition and WRC 5 FIA World Rally Championship, PS2 classics such as Wild Arms 3, Okage: Shadow King, and Arc the Lad: Twilight of the Spirits, in addition to PS4 racers like Sebastien Loeb Rally Evo and Table Top Racing.
“Today also marks the start of our summer price promotion for PlayStation Now. From today through September 25, we are bringing back the $9.99 intro offer and 12-month subscription for a limited time. Get your first month for $9.99 (new subscribers only) or lock in another 12 months of PS Now for just $99.99,” revealed Brian Dunn Sr Product Marketing Manager, SIEA. 
Here are all the new games available to stream on PS4 and PC starting today (via the official PlayStation Blog):
Adam?s Venture: Origins
Aegis of Earth: Protonovus Assault
Arc the Lad: Twilight of the Spirits
Firefighters: The Simulation
Kinetica
Okage: Shadow King
Seasons After Fall
Sebastien Loeb Rally Evo
Table Top Racing
Wild Arms 3

PS3 ? PS4 upgrades:

Sniper Elite 3 Ultimate Edition
WRC 5 FIA World Rally Championship

According to the PS Blog update, the games below were the most popular on the service during May:

Red Dead Redemption
God of War 1 (Original)
God of War 3 Remastered
Mortal Kombat
Fallout: New Vegas
WWE 2K16
The Last of Us
Sid Meier?s Civilizati...