This is the walkthrough of Trainyard, first mission of Project IGI.
Turn right and run along the building until you come to a ladder. Climb it and head straight and stop a few meters from the ladder going down. Look slightly up and to the right, and you'll notice a big water tower or something and a sniper standing on it. Pull out your MP5, zoom in, and take him out - aim low and make sure he's dead before climbing down the ladder. Take the Uzi and ammo on your right and change weapons to the Uzi. Open the door and shoot the guy - aim for the stomach and you'll kill him in a few shots. Now quickly spin left and take out the other guy running towards you. Run over each of their bodies to pick up two AK-47's.
Go out the other door and head left into the computer room. Use either computer to disable the security cameras for two minutes. Go back out and take the door to your left. Head left, run to the tower, and climb up. Take the Dragunov from the first guy you killed. Use your binoculars to spot enemies and take them out with your newly acquired sniper rifle (use alternate fire and aim for their chests). There are five enemies in all that you can kill this way.
Switch back to your Uzi, and look up. You should see a grey wire connecting the tower you're in to another tower. Use the wire (hold [Right Shift]) but first see guard near ware house in map computer that he has back at you. Once you're in the other tower, pick up the AK-47 and snipe guard near ware house and camera near small ware house.Slide down the ladder.Walk around crates and come near fence and climb it.Enter into ware house and pick Minimi.
Enter the office building and navigate your way through, picking up the two pieces of ammo on a table in one of the rooms. Once you've reached the other door to the outside,go behind barracks and run to the truck.
You start at the back of the security building. Run behind it, find a ladder and climb up. Go forward and climb ladder down.Pick up Uzi and Ammo.Switch to Uzi,open door kill guard with Uzi and wait.Another guard will came from left side.Kill him.Open next door,move left and open door,hack computer.Exit building.
Walk outside to the water tower. Climb the ladder and walk anti-clock wise around the water cistern. Use your knife again if you want and pick up the sniper-rifle. Now it's sniping time! Primary targets are marked in red and secondary in orange on the screenshot. As you can see, the cameras are targets. Getting rid of them saves you a lot of trouble later. Note that if you take out a camera or a guard which is surveyed by another camera you will start the alarm, so sometimes you have to take out the cameras in the right order. Do not shoot camera at watch tower.
Now it's time to visit the watch tower. Don't climb down! There is a electrical wire going from the water tower to the watch tower [see screenshot]. Walk up to it and look upwards and you should see the "sliding down a wire"-symbol at the bottom of the screen. Before you slide over to the watch tower, take a look a your map. Make sure that the guard patrolling in front of the large warehouse has his back to you.
Once in the watch tower, pick up the AK47 and shoot guard near large warehouse go down the ladder (push action key to activate "and camera near small garage.climb ladder", push action key again to slide down the ladder, saves time and sometimes health). Move to small ware house and pick grenades.
Now you can either climb to the roof of the small garage on which the camera was attached via some crates located at the garage's west wall or you can do as Anya proposes and climb the fence. Move to large warehouse and pick Minimi.
Walk up to the most eastern gate. Push the button to open the gate. Continue to the small garage.Get into the truck.
You can go through an another way.Move to office building. In 4th room there are two ammo boxes. Pick them up and exit through opposide side. Go behind barracks and get into the truck.