Call of Duty: Modern Warfare 2/O Cristo Redentor

Eliminate all hostiles without harming any civilians
 * Description
 * Stars
 * Regular: 1 Star (30 enemies, no more than 5 civilian casualties)
 * Hardened: 2 Stars (40 enemies and dogs, no more than 3 civilian casualties)
 * Veteran: 3 Stars (50 enemies and dogs, no more than 2 civilian casualties)

Walkthrough
Start off by swapping your Ranger Shotgun for the AA-12 Shotgun with Heartbeat Sensor and the four claymores near your starting position. You should use the heartbeat sensor to locate enemies and the TAR-21 to kill them. Then head into the building on the left. First, plant a claymore near the alleyway to the side of the building then jump through the building and throw a frag grenade or a flashbang. Kill the enemies in there then look through the window on the right and an enemy should come through the alleyway to kill you. Kill him, then slowly go forwards, to the right there will be a courtyard with a lot of civilians and enemies in it. After the civilians start running, go backwards and wait. After they have all gone, throw a flashbang or just shoot them all. After that, continue going down the left hand side buildings until you reach the end of the final building.

Go around the building and kill the enemy waiting for you, then go forward with your sights on the door in front of you. Once the door starts to open, shoot it and an enemy will die, then head for cover as more enemies and civilians appear. Wait behind cover for all the civilians to run away then throw a frag grenade over the building or shoot through the small window. One enemy may hide down the road away from the favela.

Continue going clockwise round the favela. After the alleyway, stop, quite a few enemies may enter from the left. Kill them all, then go back to the end of the alley, there should be two enemies to the right (one in a doorway and one behind a closed door). Kill them both then make your way forwards. Watch your corners, there should be a few more enemies to kill the the right. After you kill these, go into the building to your left, there should be one enemy inside a small room with a chest of drawers. Kill him then continue onwards.

Throw a grenade down the next street and shoot any barrels you see. You should be very close to completion. After all the enemies are dead, there may be a few enemies in your starting position, kill them then continue going clockwise killing enemies until you reach your target amount of kills. Be careful as when the counter gets low, there will be more enemies on the map than the counter.

Dogs: On Hardened or Veteran levels two dogs appear after every 10 enemy deaths. If you have trouble killing them go somewhere that you can climb up, like the wrecked cars at the starting point. The dogs will hold their attacks while you are above ground level, so you can just shoot them from that vantage point.