Prototype 2 is a game that deals in moderate swings. It starts out a little slow as your protagonist, the gruff and painfully stupid James Heller, gets his bearings and starts to earn multiple powers. Once it gets rolling, it's pretty fun to lay waste to everything around you as you unlock arm swords, arm whips, claw arms, and so on. But once you get most of the powers and move into the game's back third, it turns into a monotonous chore. I had unlocked almost all of the meaningful upgrades, and all that remained was to trudge through the remaining story missions to see how the story ends. But the story in Prototype 2 is filled with one lame character after another, making Prototype 2 a much better game when it just shuts up and lets you break stuff.
This sequel flips the original game on its head by making the protagonist of the original, Alex Mercer, the bad guy here. At the opening, Mercer infects your soldier with his crazy virus, giving you the same abilities Mercer had in the original game, such as gliding and air dashing, which makes floating around the city pretty easy. You can also run up the sides of buildings, pick up cars, and all sorts of other superhero-style stuff. The thing that gives Prototype its hook, though, is the way you can "consume" other humans and steal their shape. This gives the game an occasional stealth edge, as you'll sometimes need to consume the commander of a base and assume his identity to make your way past locked doors and such. The game won't let you eat people in front of other people without causing a full alert, so you'll either need to take out the enemies that are looking in your direction--which the game helpfully points out--or just cause an alert, eat your target, then run away until the alert dies down. You can swap between your real form and the most recent person you've eaten at will, and switching when enemy troops aren't looking in your direction cancels that alert status almost immediately. So the stealth side of Prototype 2 is light, at best.
The backdrop for your cannibalism is a quarantined New York City, which has plenty of regular civilians around mixed in with evil military guys, even-eviler Blackwatch troopers, monsters caused by the infection, and a group of "Evolved" humans that are just like you... but evil. Each enemy requires slightly different tactics at first, but as you level up and unlock new abilities and complete side tasks to get bonus mutations, the opposition isn't a significant threat. Enemies that originally require you to dodge or counter their attacks early on in the game are defeated by simple button mashing later on. While that ties in nicely with the way your XP is constantly giving you more and more power, it makes the back third or so of the game feel like a formality, from a gameplay perspective.
So much of Prototype 2 and your enjoyment of it hinges on you enjoying the way Heller moves. As with Mercer in the previous game, Heller can run up the sides of buildings, glide, and air dash his way around New York, and upgrades you earn along the way make all of those things work better, as well. Combining your various movement abilities to quickly get around the city is probably the best part of Prototype 2, but it still has some clunky moments, like the way Heller seems to want to run upside-down whenever you're dashing up the side of a building with an awning. When you're attempting to complete one of the game's time-based challenge missions, those little glitches become pretty frustrating. But you'll only run into a few of those if you stick to the main path.
Sticking to the story path will get you through the game faster, but you'll miss some of the cooler upgrades. In addition to earning experience points and leveling up, completing sets of side missions gives you access to various mutations that can alter your character in some interesting ways. One, for example, lets you simply ignore all hits from small arms fire. When bullets just bounce off of you, you can focus on the larger threats, like the big mutant beasts that want to rip you in half, tanks, choppers, or dudes with rocket launchers. Other mutations give you more mobility, and so on. The side missions also tie into the old "Web of Deceit" concept from the first game, where you hunt around the city for specific individuals and consume them. This gives you a look at their thoughts, which helps fill in a bit of backstory, and it also gives you the computer access required to learn about enemy troop movements and other intel that turns into missions where you travel to a location and, generally speaking, destroy everyone that gets in your way.
If you purchase a new copy of the game (or pay for separate access, which I wouldn't recommend), you'll get access to another tier of missions. Some of these are more like little minigames, where troops are set up in formations and you have to figure out the right way to dive-bomb and take out as many of them as possible. Others are more achievement-like, asking you to rack up a set number of kills with a grenade launcher. Completing these sets of time-release missions gives you bonus material, like an Alex Mercer skin for use in the single-player. Boy, that sure doesn't make any sense in the context of this game's story. Some of them make for interesting diversions, but as a whole, there are already more than enough side missions in the game, and filling it out with even more turns the game into busywork.
That's probably the biggest problem with Prototype 2. Its cooler moments are offset by a long list of missions that aren't engaging at all. You're a man with an ever-increasing list of insane powers, but the tasks you accomplish with those powers are usually pretty ho-hum. Add to all that a script that makes you want to turn the sound down and a dose of awkward control quirks and you've got a run-of-the-mill open-world game.