Combine a bit of Mirror's Edge, Assassin's Creed, Spiderman, and maybe a little Grand Theft Auto, and you have Prototype
Gameplay - So fun that I spent to much time just hijacking helicopters and blowing up police stations. That said, when it was time to really get into the meat of the game I was pretty buffed out with xp and I was never really challeged, or killed more than 5-6 times. (except the final stage--that was a bit rough) Regardless, it was still an absolute blast running around causing carnage. There were plenty of upgrade abilities to be had, and some of them took the game to a whole new level. Being able to soar from building to building was cool enough, but to drop down from a skyscraper and take out the bad guys was just a rush. In fact, that was one of the best parts about this game...want to hit the action and get a rush, you can stir up trouble at any time. Want to take it easy and exlplore, go right ahead.
Storyline - Amazing and this was another case of a bit to much time spent watching the endless cut scenes. Some of them were disturbing and twisted, which made the storyline all the more engaging.
Overall - I have never been a big fan of open ended GTA type games, but this one has broken me of that issue. An absolute must have, and with a few changes to the AI and side-quests, this game could have hit a 9.5.