Rocket League +1, and it’s under a tenner on the PS Store at the moment.
Maybe not a hidden gem as such, but it’s received so much bad press from folk who saw the development spiel and decided it was going to be a completely different game to how it actually turned out, and as such people may be put of it: No Man’s Sky
I downloaded it on a whim (seeing as it was only £20) yesterday, let it do its update thing and then switched it on about 10pm to see what it was about. Next thing I know it’s 4am and the wife is asking why I haven’t come to bed yet. A gentle-bimbling-aroundy, shooty, collecty game that I really like.