Helldivers is awesome fun - I'm been dropping in random matches as I have no ps4 friends and its hilarious.
I can do up to lvl 10s so far great fun, shooting each other is the best bit!
Funniest so far was when I joined a match, and it dropped me on all three team mates in an APC killing them instantly. I then proceeded to get chased off a cliff by bugs. Game over!