This is essentially a port / hack of Shadow of the Demon Lord with more swearing (a lot more swearing, over 300 F-bombs in a sub-200-page PDF, to the point where reading it is honestly kind of tiring) and some extra rules bolted on. Fair enough, it's not trying to pretend to be anything else, but, despite typically strong SchwalbEnt layout and production values, many of those extra rules feel quite rushed. There's a charisma / personality table despite charisma being a numerical stat now (I guess because Demon Lord had one). Speaking of which, there are now eight stats rather than four and I really don't understand why - Demon Lord did just fine with four, and the elegance was honestly part of what I liked about that game.
What really sunk this game for me, though, was the firearms rules. As written, they're pretty much unworkable. Every single gun in this game has a 1 in 3 chance per attack to fail, either jamming or blowing up in your face; bizarrely, this is actually much less reliable than the black powder weapons of Demon Lord. I'd get this if the game downplayed guns, but they're everywhere in the art and setting to the point where bullets are your basic currency.
Between this, the stat split, the wonky mutation rules, the tone, and a pretty uninspired setting which I think is trying to be satirical (but the fact that it's hard to tell isn't a great sign), I really can't recommend PunkApocalyptic.