Prototype offers a unique twist to the open-world genre. And (for the most part) it works!
-Cool story
-Awesome super powers
-Combat is fun and bloody
-Several missions outside of main story
-Upgrading your character is simple and efficient
CONS
-Awkward aiming mechanic
-Dull textures/ environments
-Difficulty can seem uneven at times
Prototype starts out with a whole lot of questions: who are you, what happened to New York, and how did you get your powers certainly come to mind. First off you're Alex Mercer. You've been experimented on and you don't remember anything other than that and your name. New York is pretty F'ed up because a virus has been unleashed and is spreading throughout the city- turning people violent and...zombie-like. Your powers were a result of a harsh experiment - and thats all I can say about the story without spoiling it!
Gameplay in prototype is open world. Typically you'll be on the ground or in the air, but hardly ever in a vehicle because: 1) You can run really fast and smash anything in your way and 2) you can glide and jump really high. Through the world map you'll access missions via glowing hubs-simply stand in the center and hit "Y" to begin. There are multiple outside the main story and all are interesting and entertaining. They consist of time trial races, short killing sprees for points, gliding and landing in a good spot, and many more. On top of the multiple missions you have the option to go into military bases and cause some havoc- it's pretty fun.
Combat in Prototype is essentially easy to learn and hard to master- light attacks are X and heavy are with Y, B is grab, combine X and Y to do combos, etc. Whats interesting is how you use your different powers and the available weapons you can grab. You can also absorb the likeness of soldiers and stealthily blow everything away with an airstrike. The problem is targeting. At times there are too many enemies on screen that the targeting interface focuses on- making it awkward to hit what you want to attack.
Overall though, Prototype is a rewarding and interesting game that everyone should at least try.