Even though, as far as I know, Activision says there is not a glitch, there is. after you complete a misssion, sometimes the next mission will disappear. My suggestion is to make a new save game after every mission so that you can go back a little bit and continue. I did not do that and got half way done with the game when the glitch got me. It is a fun game, but not fun enough to start over.
"Prototype 2" returns us to an infected New York, except this time instead of playing the first game's protagonist Alex Mercer you now play a returning soldier named James Heller. Heller's wife and daughter are killed, and Mercer infects him with what is now called the "Mercer virus". So Heller now becomes a killing machine, with increasingly stronger powers and abilities as you progress through the game. The game is divided into three zones (you can backtrack to a zone after you've finished all of the main story missions via a fast travel point called an air bridge), and there are 32 main missions divided among them. In addition to the main missions, there are 12 side missions to tackle and collectibles to find. Controls are fairly smooth once you get the hang of them, though on occasion they'll delay in engaging (the glide mechanic is good for this). Heller's hunt ability, a sonar like pulse he can emit when tracking a target, is a neat idea, but in practice it proves to be more confusing than helpful. This leads to plenty of frustration when your mission is to find a certain target. Thankfully, most of those are side tasks that you can ignore if you want. Voice acting is fairly good, though the dialogue is especially profanity laden, so keep that in mind if you have youngsters in the house. The story is decent but forgettable, as it basically retreads the same tale from the first game but with a different lead. Missions don't vary much- infiltrate a base, steal an identity, kill things- but they're fairly fun. The camera, just like the first game, can get a bit crazy in chaotic combat. Graphics are nice and detailed, though the print is a bit small and can be hard to read. This game makes for a good rental, as it's a fun way to kill time but it's hardly a memorable experience. Heller as a character just doesn't make a big an impact, as, say, Cole from the inFamous games. Still, it's worth the time to play. Even if you'll forget it soon after you return it.