For the past couple years, Sony has run a week-long sales event focused on co-op games. This joyous time for us co-op gamers usually runs towards the end of November (just in time for the holiday season), but it appears that it's getting an earlier start this year. From now until 8:00 AM Pacific on September 20, you can take advantage of good deals (up to 70% off in some cases) on some great co-op titles like Diablo 3: Reaper of Souls - Ultimate Evil Edition and Dark Souls 3.
You should check out the page on the PlayStation Store for the full list of games (some of which are definitely not co-op), but here are a few standout titles we saw on there:
Tom Clancy's The Division Gold Edition (includes Season Pass) - $59.99 Dark Souls 3 Deluxe Edition (includes Season Pass) - $67.99 Diablo 3: Reaper of Souls - Ultimate Evil Edition - $34.79 Dying Light: The Following - Enhanced Edition (base game, all bonus content, and the Following expansion) - $34.99