Path of Exile is the closest thing you're going to get to Diablo without spending a penny. The action role-playing game has been popular on PC for quite some time, and today (that's the 26th March in case you're reading this later), the game has finally hit PlayStation 4.
Complete with mountains of loot and a truly gigantic skill tree, Path of Exile aims to keep you entertained for hours on end, and, as mentioned, it's totally free to play. The best part? There are no "pay to win" items -- developer Grinding Gear Games has been hard on that stance for a while.
Path of Exile is available on the PlayStation Store right now, although you may have to search for it directly. Let us know if you're going to give this one a try in the comments section below.