I loved Hollow Knight, but never finished it.
My list of PS indies goes like this
-Journey (easy game, short game, but it's a meditative adventure that the whole family can enjoy - it was first released on PS3, but still looks good)
-Hollow Knight (hard, but fair, best metroidvania in years)
-Celeste (didn't play it, but heard the story is great)
-Terraria (I believe it's on a list of top20 most sold games of all time)
-Inside and Limbo (both from the same studio, if you like one, you'll like the other, also both are usually cheap)
-Unravel and Unravel Two (the second one can be played co-op)
-Shovel Knight (it's a cute, challenging game)
And if you have another person that can play with you, A Way Out, Brothers and It Takes Two from the same studio, Hazelight. It's very fun.
And my favourite indie game of all time - Hades.