Shank's fatal flaw is that it does nothing besides look pretty and be excessively violent. You might think that those two things would be enough, but no.
This is a 2D brawler that takes the linearity the genre requires so seriously that it gives you nothing else to do but go from left to right. It's like reading a two-panel comic that's repeated ad nauseam. And those two panels are just: Fight these goons. Do some platforming. Fight these goons. Do some platforming.
Borrowing art styles from the likes of The Venture Brothers and other Cartoon Network staples, Shank tells the tale of a very angry man who was left for dead while his girlfriend was kidnapped, who now must hunt down and kill every member of the gang that did the deed. Luckily they each have an army of henchmen, drawing things out immeasurably.
And so you fight, and fight, and do a bit of jumping, and fight some more, to the point of your mouseclicking sounding like an overexcited Geiger counter.
Unlike Diablo, or the other seemingly one-note games, there's nothing peripheral happening here. You're not chasing loot, or levelling up your character; you're merely slashing, shooting and chainsawing everything that gets between you and the right-hand side of the screen. Endlessly. Bloody violence has never been so boring.
The boss fights themselves would be a welcome change of pace if they weren't so doggedly trial-and-error. It's never immediately apparent what you're expected to do, what secret, clever thing makes a boss vulnerable, so for your first try you're just flailing wildly at them until they inevitably kill you. Then a message pops up letting you know exactly how to dispatch this enemy and suddenly all difficulty is removed. It's two equally unwanted extremes in one boring box.
There could have been genuine fun here if the combat had depth, but it's driven by a frustrating system that sees you locked in animations that sometimes take seconds to play out: it doesn't matter that you desperately want to block an incoming kill shot, it needs to show you desperately shoving a grenade in some guy's mouth.
The one saving grace is that it's very pretty, and occasionally does interesting things with its 2D format, such as having you fight in silhouette in front of a huge neon 'GIRLS GIRLS GIRLS' sign. You can kind of lose yourself in the monotony of it all, but really, unless you've got excessive amounts of time to kill, you should probably look for something a little more engaging. By the time you get near the end of the game, the checkpointing becomes so bad, the difficulty ramped right up, that you're better off packing it in rather than continuing. You know what happens, anyway. He kills the bad guy and gets the girl.