Mercenaries 2

Total Video Game Dominator. Worth: $60
based on 360 retail game

Creative. Violent. Awesome.

Guns, rockets, grenades, C4, artillery, missiles, tanks, helicopter gunships, recoilless rifles, 500-pound bombs, jet-propelled water craft, and earth-penetrating nuclear bunker-busters. This action game literally has it all for you to reduce Venezuela to a smoldering ruin.

Controls, camera, driving, environment.
The controls are pretty different from other action games, but once you get used to them they're fine. The camera is solid (unlike GTA4), the driving is fluid and fun (unlike Crackdown), and the world is wide-open and sprawling (unlike Halos 1-3).

Missions
Your tasks range from small (kidnapping/eliminating specific people) to large (destroy off-shore oil derrick). The story also ranges from cozy things like talking to your co-workers (the drunken jet pilot is pretty funny) to real-world issues like the way oil-hungry superpowers stomp all over the rights of third-world countries that happen to sit on large petroleum reserves.

Come for the bombs, stay for the Co-Op
Playing this game with my buddy Arth rivals Halo 3's co-op for best-ever video game experience. In many ways, it surpasses it because you really can go anywhere and do anything (pretty much). There are at least four or five ways to accomplish each mission, and with two people that number doubles. You can run in shoulder-to-shoulder, or ride in a tank together, or have one person in a helicopter providing cover fire while the other assaults on foot. The AI will do what it can to spoil your plans, and that's when the ability to improvise comes in handy. Arth and I have good communication with each other because we've played so much Halo 3 MP together, and we both like creating gigantic exploding fireballs out of things that bar our path to total video game domination.

Example story
Arth and I had just finished a job when we got attacked by two tanks, a company of enemy infantry, and a huge helicopter. While Arth fought off the ground forces, I hijacked the helicopter. Then I used the chopper's anti-tank missiles to obliterate the enemy armor. By this point Arth had cleared out the foot soldiers, so I swooped down and picked him up. He got on the door-mounted minigun as I flew us up to about a thousand feet. Suddenly two enemy helicopters appeared and fired anti-air missiles at us. Arth managed to kill one of the pilots before the enemy rockets blew our ride into an airborne junkpile. Arth and I fell to earth (both of us laughing all the way down, it was totally comic-book ridiculous) and got our health knocked down to 1% each. We both took cover while the remaining enemy helicopter circled the area. Arth broke cover to draw the chopper's fire while I rushed underneath the circling menace and hijacked it. After throwing the pilot out the window, I picked up Arth and we flew off into the sunset. This kind of adventure happens every time we play together.

Mercenaries 2 could be the game of the year, and I give it my highest recommendation.

UPDATE: Sep 19. Arth and I just found the Fuel-Air RPG. It creates a cloud of gasoline vapor (very dangerous!) around your target. Then the cloud explodes in a giant fireball. It's a guaranteed kill on whatever it hits: tanks, bunkers, buildings, anything. Terrific!

UPDATE Sep 20. We found the MOAB (Mother of all Bombs). It destroys at least two or three square acres. Arth and I must have laughed for about ten minutes after we saw how ginormous this friggin' this is. When the bomb came out of the plane it was like the bomber gave birth to a city bus.

UPDATE: Sep 22. Arth and I have taken to racing the game's motorcycles off cliffs and over steep hills to get as much air as possible. We've even discovered our own personal Achievement. We call it "Ghost Rider" and the idea is to get your bike to burst into flames at the beginning of a jump so you create a fiery arc across the sky before the bike explodes in mid-air. We've spent the last two nights doing only this. This game is totally hilarious.