The Blacklight virus is back in New York, and doing its horrible-mutation thing again.

In 2009’s “Prototype,” you played as Alex Mercer, a man with spotty memory and bizarre shape-shifting abilities who discovered that not only did he embody the Blacklight virus (the science here is suspect), but his original self was the one who unleashed it on Manhattan, leading to the deaths and mutations of countless people.

In “Prototype 2,” you play as a different man, James Heller, whose wife and daughter were killed in a new outbreak of Blacklight. Bent on destroying the resurfaced Mercer, whom he blames, Heller finds himself infected by a strain of the virus by Mercer himself, which grants him powers similar to those of his foe.

These two monsters have, if not an alliance, at least a common foe in the brutal soldiers of Blackwatch, the shadowy military group occupying the city, and the depraved experiments of Gentek, the company that created the virus in the first place.

Heller’s new abilities allow him to consume and absorb people, learning their useful memories and taking on their shapes so he can travel in restricted areas without challenge. He can change his limbs into weapons such as claws, blades and sticky tendrils, form thick shields from his arms, run up walls, jump high and far, and glide from heights to travel long distances — and that’s just the basic stuff. More dramatic powers allow him to dive into the pavement from a height to send a wave of spikes out from his impact point, for one example.

Heller’s powers grow as you reach certain points in the story line of the game and gather the DNA required to evolve into new forms. Like Mercer, he becomes a nearly unstoppable creature capable of tearing apart helicopters and tanks with ease, though he will face larger threats in the form of viral mutants and amped-up super-solders.

“Prototype 2” plays much like the first, with various characters offering missions that propel the main story line, and additional optional challenges scattered around the New York cityscape (which is broken up into three zones by level of viral infestation).

Also like the first game, this one is tremendously gory and indiscriminately violent — Heller’s deadly implements don’t have much precision, and while the game doesn’t really encourage killing the civilians that wander the streets, skirmishes with Blackwatch soldiers and mutants are certain to kill some bystanders as well.

Heller isn’t outright evil like the psychotic soldiers and ravening monsters he fights, but at best he’s a well-intentioned anti-hero with huge potential for collateral damage. Being a Blacklight mutant comes with advantages, but it’s hard to be the good guy when you can depopulate a city block by accident.