This page of the guide has a walkthrough for chapter 12 of Uncharted 2: Among Thieves called A Train to Catch. You need to get a weapon to be able to kill enemies. Hide behind signs and walls to avoid snipers and other "elite" opponents.
This chapter focuses more on traditional fights. Chapter 12 provides various ways in which you can kill enemies - you can fight from behind covers, hanging down from signs or by hiding in a train car.
This chapter has five treasures. Most of them are in plain sight, however, they can still be missed rather easily.
Difficulty level: medium
Number of opponents: small
Chapter type: combat
You start with no weapons. Leave the building and go to the left edge of the roof/balcony. Hang down from it and jump on the ground (try to remain undetected).
There are five enemies here and you can defeat them all without raising the alarm. After you jump to the ground, run towards the destroyed building and crouch under the window. Wait until the enemy inside turns around (photo on the left) and jump inside. Get closer to that enemy and kill him. Don't leave the destroyed building. Run towards the damaged wall on the right (look in the same direction as in the picture on the left) and eliminate the next opponent patrolling the area. Wait for the enemy and grab him when he passes you by.
There are only two opponents left on the ground. However, they are better equipped. To eliminate them, go to the door of the building and look out on the street. You should see them both. Run outside when both of them are turned around. You must be quick - you need to attack the second opponent before he turns around [secret 1].
The last opponent is on the nearby roof - and you will get there by climbing the ladder. Go up and hang down from the edge. Then, get close to the enemy and throw him over the wall.
Wait for Elena to join you. You need to boost her. She will lower the ladder for you. Go up [secret 2], jump over the barrier, and to the next roof.
This way you will reach the closed gate. To open it, jump towards the signs in the central part of the square. Grab the largest orange sign and aim at the three boards blocking the passage from the other side.
After that, you will be attacked by enemies. The path leading back is cut off - you are stuck on the sign until you kill all the enemies. They will appear in three waves. Remember to switch the signs' sides to avoid getting hit. Don't forget to throw grenades at the enemies.
Once the last opponent is dead, the journalist will lower the footbridge [secret 3]. Use it and then jump on the roof on the right. After that, you need to climb the ladder.
Watch the cut-scene and then go to the rope leading down to the train cars, and press the Triangle. Drake will reach the door to the big hangar [secrets 4]. To get inside, you have to move the cart with the bags blocking the door.
While inside, run to the freight car and climb to the large window. Jump on the cargo to reach the train car closer to the center of the hangar (photo on the right).
Jump on the yellow metal footbridge [secret 5] and then on the passenger car (on the right, if you look in the direction of the entrance). Reach its end and pull the lever.
Watch a short cut-scene. Drake will attract attention of a huge number of opponents. You will be attacked from all sides. Fortunately, the authors have provided a lot of ammunition and grenades. When the fight starts, try to kill a few opponents coming from the front (you can use grenades, but try to save some for the very end of the battle).
When you see a red laser, it means that snipers appeared on both sides of the car. Stop fighting the enemies in the front and focus your attention on the new threat. A sniper rifle lies on the left (if you look in the same direction as in the picture below), right under the window. Use it to kill the enemies located farther away. Remember that this weapon is also effective at a short distance. However, you shouldn't aim through the scope.
At some point, after the snipers are dead, the game will play a short cut-scene. You will be attacked by two heavily armored enemies equipped with heavy machine guns. They are the reason why you had to save up some grenades (at least two). Slow them down by throwing grenades. Soon, Nathan will be saved by Elena. This ends the chapter.