One Word: Auger.
The game begins in alternate history 1957 with a recap of the events that closed Resistance 2. *Minor SPOILERS* Due to the death of protagonist Nathan Hale at the end of Resistance 2 you pickup the continuation of this tale as fellow SRPA member Joseph "Joe" Capelli. For those fans of the series you will remember that it was Joe who killed Nathan when he began to turn into a Chimera at the end of the game. For this Joe was dishonorably discharged from the service and so decided to give up the fight against the Chimera and settle down to raise a family in Oklahoma. *End SPOILERS* Humanity has lost the war and the remnants live a stoic existence in underground tunnels. The Chimera continue their efforts to terraform the Earth to better suit the colder climate they enjoy. As the game begins a Chimeran death squad has come to the community of Haven, Oklahoma were Joe and his family live. As Joe you take on these forces before learning that they followed Dr. Malikov (the world's leading scientist on all things Chimera) to your town. After an exchange of angry words Malikov reveals that he came in search of you to enlist your aid in destroying a wormhole generator in New York City that is essential to the Chimera's plans for Earth in some unknown way. Eventually with encouragement from his wife Joe agrees to make the attempt.
The game has a story campaign that can be played single player or cooperatively via splitscreen or online coop mode. The campaign can be completed in roughly 8 to 10 hours in single player and likely a bit less on normal difficulty in coop mode. A higher difficulty setting is recommended for a challenge in cooperative mode as the game seems designed primarily as a single player effort for the story campaign. What sets this game apart as an FPS is the variety of weapons and their secondary fire modes. Every weapon has a unique style and all of them have a secondary fire option. You start the game with the Bullseye, a Chimeran machine gun that has a secondary fire option that lets you tag an enemy and hit them with each successive shot regardless of where your gun is pointed. You also get the HE .44 Magnum, whose secondary fire lets you detonate a round after its been fired causing additional splash damage. The Auger is another Chimeran weapon that allows you to see and shoot your enemies thru walls. It also has a secondary fire mode that allows you to create an energy shield that only Auger rounds will pass thru. This weapon is useful even when you're low on ammo as a way to scout ahead for enemy positions. There are many more weapons available in the game and you have access to all of these weapons at any time once you acquire them via the games weapons wheel (which makes its return from Resistance: Fall of Man). The game also sports the now somewhat unique trait of having health packs in place of regenerating health. This adds a definite bit of tension and an acquiring of a level of skill throughout the game.
The game has good pacing and varied level design so as to keep you gawking at the environment and worrying about what threat may lie around the next corner. The AI can get a bit spotty at times. Sometimes your enemies will just stand there dumbly while you lob rounds into their back or make an open dash straight for your position allowing them to be easily picked off. The gameplay experience definitely varies between playing alone versus playing cooperatively with a friend. Your actions and use of ammo and health packs are a bit more tentative when playing alone whereas your style becomes more visceral and in your face while playing coop as your enemies can be taken with greater ease as a team. I've seen where some have said that the games story ending is anti-climactic but it pretty much ends in the way you would expect. The story is wrapped up neatly and the possibility of a sequel is not completely ruled out.
The game also has a great online multiplayer component. As this is an FPS the standard modes are available: Deathmatch, Team Deathmatch, Capture the Flag, Objective Modes, Chain Reaction, and Breach (a mode in which you attempt to either destroy or defend an enemies base). Lag has been a bit of an issue with some matches but the developer assures that they will continue to release patches to improve the gameplay experience. Insomniac has done a good job of linking the single player and multiplayer components to make various unlockables available only by playing the single player campaign. There are also unlockables for the game that you can receive by playing and linking your online RTS game of Global Resistance located at http://www.myresistance.net/global. The game also supports PS Move and the use of the Sharpshooter peripheral. This is a fun and engaging way to play the game although it does make your arms tired and their is the possibility of a feeling of vertigo with prolonged periods of play. In the end this game is another must have for the FPS and PS3 fan.