Use a mounted turret and begin shooting. Have a friend punch or kick you off of the turret while you are shooting. You will now have unlimited gun and grenade ammo.
Complete the following achievements to unlock Xbox Live Gamerscore points.
First Hurdle (20 points): Survive Agent Diagnostics and earn deployment into Pacific City.
Get Connected (20 points): Locate and activate an Absorption Unit, alone or with another Agent.
Plugged In (50 points): Locate and activate every Absorption Unit in Pacific City, alone or with another Agent.
Big Bang (20 points): Oversee the deployment and successful detonation of a Beacon, alone or with another Agent.
Hope Springs Savior (50 points): Detonate every Beacon in Hope Springs, alone or with another Agent.
Green Bay Savior (50 points): Detonate every Beacon in Green Bay, alone or with another Agent.
Unity Heights Savior (50 points): Detonate every Beacon in Unity Heights, alone or with another Agent.
Light Bringer (20 points): Detonate every Beacon in Pacific City, alone or with another Agent.
All Under Control (20 points): Secure all Tactical Locations within one Cell stronghold, alone or with another Agent.
Location, Location, Location (50 points): Secure every Tactical Location in Pacific City for the Agency, alone or with another Agent.
Pest Control (10 points): Clear out and close down a Freak Breach, alone or with another Agent.
The Closer (20 points): Close down every Freak Breach in Pacific City, alone or with another Agent.
Tower Power (20 points): Complete the final phase of Project Sunburst at Agency Tower, alone or with another Agent.
Tellin' Stories (10 points): Collect and listen to an Audio Log.
Closed Book (20 points): Collect and listen to every Audio Log in Pacific City.
In Plain Sight (10 points): Find and collect a Hidden Orb.
Sixth Sense (30 points): Find and collect every Hidden Orb in Pacific City.
First Rung of the Ladder (10 points): Find and collect an Agility Orb
King of the World (50 points): Find and collect every Agility Orb in Pacific City.
In the Net (10 points): Catch an Agility Renegade Orb or Driving Renegade Orb.
Renegade Runner (20 points): Find and collect every Renegade Agility Orb in Pacific City.
Renegade Racer (20 points): Find and collect every Renegade Driving Orb in Pacific City.
Speed Demon (10 points): Complete a Road or Rooftop Race
Street Racer (20 points): Complete every Road Race in Pacific City.
Rooftop Racer (20 points): Complete every Rooftop Race in Pacific City.
Wingsuit Racer (20 points): Glide through every Wingsuit Stunt Ring in Pacific City.
Stuntman (20 points): Jump a vehicle through every Vehicle Stunt Ring in Pacific City.
LIVE and let LIVE (10 points): Collect every Online Orb in Pacific City.
Who's the Daddy? (50 points): Develop each of your skills to their maximum levels.
Solid Block of Orbsome (50 points): Find and collect every Agility, Hidden, Renegade and Online Orb in Pacific City.
Jack of all Trades (20 points): Complete one of every objective type in Pacific City.
Pebble Dash (10 points): From the top of full-height Agency Tower, leap into the chimney stack and live to tell the tale.
City Glider (10 points): Wingsuit glide through the airspace of all islands in Pacific City without touching down.
Squad City Glider (20 points): 4 Agents, Wingsuit-glide through the airspace of all islands in city within 30 secs of leader.
Open up a Can (10 points): Kill 5 enemies with a single gas cylinder.
Co-op Keepy-Up (10 points): Pass a vehicle back and forth between Agents 3x using UV shotguns. Vehicle must not hit the ground.
Yippee-Kai-Yay (10 points): Drive an Agency SUV into an airborne helicopter.
Strike! (10 points): Kill 25 Freaks with thrown objects or vehicles.
Victory Roll (10 points): Alone or with another Agent, kill an enemy with a mounted turret while airborne and upside-down!
Mosh Pit (10 points): Land 20 successful hand-to-hand attacks in a chain. Under 3 secs between attacks to chain them.
Scarface (10 points): Use the minigun to amass 20 enemy kills in a 10 second period.
Zero Factor (10 points): Use a UV weapon to amass 20 Freak kills in a 10 second period.
Street Sweeper (10 points): While driving a vehicle kill 5 enemies in a single power slide.
Pin Cushion (10 points): Use Harpoon Gun to pin 5 enemies to a single vehicle.
Bomberman (10 points): Create 30 explosions in 60 seconds.
25 Ways to Die (10 points): Find 25 unique ways to destroy your cloned body.
Car Jump (10 points): Leap from one fast moving vehicle to another.
Chopper Stomper (10 points): Leap from an airborne Agency helicopter and using a Ground Strike, kill at least one enemy.
Party Bus (10 points): Four Agents; one driver and three gunners, on a Battle Bus. Must jump through a Vehicle Stunt Ring.
Pile Driver (10 points): Kill 5 enemies with a single Ground Strike.
Complete the indicated task to unlock the corresponding Avatar Award.
Freaky slippers (male and female): Earn the "First Hurdle" achievement.
Level 1 Agent suit (male and female): Earn the "Light Bringer" achievement.
Official Agency hoodie (male and female): Earn the "Jack of all Trades" achievement.
Orb Shirt (male and female): Have the "First Blood" achievement from the original Crackdown on a saved game file on your hard drive.
Ruffian hat: Earn the "Hope Spring Savior" achievement.
* Press Up to get a quick view of nearby orbs on the mini-map. You can repeat this after a few seconds.
* Use the following trick to find all the non-renegade orbs faster. Press Start during game play, then quickly press B, Up and look at your mini-map. It will be zoomed out, and it will also make the orb ping (Up) work in a much greater range. It will show you more orbs around you, and in a bigger area, which will in turn allow you to find the orbs faster as long as they are not renegade orbs.
* With an Agility 4 or greater, get a helicopter from the Agency tower and fly it as high as possible. Click and hold the Left Analog-stick to activate its jets to force the mini-map to zoom out as it moves faster. Tap Up to begin scanning for orbs.
Easy Vehicle Stunt Rings
Have two players in an online Co-Op match. Have one player in a helicopter from the Agency Tower and the other player in an Agency Supercar or Cruiser. Have both players meet at the Stunt Ring. Equip the Mag Grenades and attach one to the bottom of the helicopter and another one to the roof of the car. Have helicopter fly the car through a stunt ring. Avoid the explosion from the Mag Grenades and repeat as many times as desired.
Easy Agility Orbs
* Fly a helicopter from the Agency Tower high above the Agility Orb. Note: Jump out and drop down onto the Orb. Note: You must be at a low enough altitude to survive or have the Glide suit. The Orb will not start moving until you are very close to it.
* Use the following trick to easily get level 5 agility orbs (on top of buildings), even when you are level 1. Have a high agility level friend in multi-player mode climb to the near top of a high building with a level 5 Agility Orb on it. At the edge of the building, have him throw a magnetic lock (Mag) to where it is still on the vertical side of the building. Then, have your friend jump (glide if necessary) down and wait for you to climb on top of a nearby car. Then have your friend throw the other Mag on top of the same car. The car should be pulled up to the top of the building, so you can get the Orbs.
Spawn at the Agency tower. Note: It is recommended that you get your Agent's agility up to level 5 so you can have the Wingsuit. Once you spawn, move to the right and look for a large cylindrical pipe directly in front of the Agency Holding Pens building. It will be very tall, and is the only one that has an opening at the top. Jump down, but be careful; it is a very long drop. Use the Wingsuit's glide ability to slow your descent. You should find yourself in a small cave, in which there is a very large toilet with rubber duckies and beach balls.
* Use the following trick to find a helicopter with weapons. Spawn at the Agency island. Look at the gate to the bridge. Climb up the building to the right of the bridge. Look straight ahead after climbing to see a landing pad with four helicopters on it. Note: Level 5 Agility is required to reach them. Note: The helicopter closer to the Agency tower, and across from that, has missiles. The other two have machine guns.
* Use the following trick to find a helicopter with guns. Spawn on the island northeast of the Agency island. Once in the middle of it, climb the highest tower there. When you reach the middle level (with the free standing balconies), you will find a helicopter with no guns.
Use the following trick to find Quacker grenades (exploding rubber sticky ducks). Go to the carnival located on the island southwest of the Agency tower on the southern tip of the island. Look for the Chucks Ducks 2 booth after you clear out the cell stronghold there. Inside the booth are Quacker grenades behind the counter.