The mission starts with a little dialogue. You have no weapon. Open the door when you are told and kill the first guard. You will automatically pick up the hatchet. Look to the left outside of the cage that brought you to the mission to find intel on the floor in the shadows. You may be caught by the helicopter’s spot light when picking it up.
Stay in the shadows and don’t alert anyone. Follow Reznov and do exactly what he says. When you see another marker over an enemy do not wait for Reznov, kill him immediately and pick up his AK74u. Follow Reznov a bit more until you reach a ladder. Climb the ladder and melee the man up top. A checkpoint will FINALLY appear. The newly acquired weapon is the KS-23.
Follow Reznov into the Soviet lab. Inside you’ll find a few caged monkeys. Kill 7 of them in under 10 seconds for an achievement/trophy. Watch every window and every corner, this place is full of men with guns. Make your way through the two labs to the left to reach a checkpoint and another giant circular lab. Use the consoles in this lab for cover. In the middle is a gas chamber. Inside the gas chamber is intel.
Clear the lab and get to the room upstairs for a cutscene.
When you have control again you will be in a tank like vehicle. You can use a grenade launcher and a machine gun, but you won’t have control over the driving. Fire the machine gun at any moving targets. The machine gun will overheat if you fire too much, fire in bursts if there are lots of enemies. Use the grenade launcher on any vehicles. One grenade will take down any vehicle. There’s not much you can do but have quick reflexes, smooth aim, and good luck. This is what they call a rail shooter. You cannot take any cover and the higher difficulties give you lots of trouble.
After a short while you’ll get off the vehicle. Your weapons are a HK21 w/Drum Mag, Enfield w/Infrared Scope and masterkey shotgun, and 4 grenades. You will have a hazmat suit to protect you from the Nova 6 gas. If the suit get punctured you will die instantly. The suit can take a few shots, but it won’t regenerate like your health unless you die and respawn at a checkpoint. Make it through the gas without dying and you will unlock an achievement/trophy. Enemies will continue to come at you through the thick smoke. Use the IR scope to see through the smoke. Enter the building to your left at the end of the street. Use your IR scope again when you reach the door to exit the building. There will be many people at the end of the street shooting towards you. Move forward with your team and make your way towards the next building. Before you enter the building you can find another intel. Look to the right to find a small house with it’s door open. Inside on the counter is the intel.
Enter the other building and head upstairs with your team. At the top you’ll find a door leading outside to another building. Enemies are at the windows of the other building and outside on the ground. Stay out of sight and pick them off with your Enfield. Reach the objective markers but stay on guard. Go through the building across the roof tops or jump down and climb up the stairs to enter the next building. On the other side you’ll find more enemies and two helicopters. Kill the men on the ground and pick up a strela rocket launcher to destroy both helicopters.
Keep moving until you exit the gas. You should be at a parking lot. Look all around for enemies. There are men behind cars, up stairs, in the windows, and on the rooftops. Your objective is to infiltrate the soviet lab and capture Steiner. Clear and enter the lobby. The next marker is to the left down a hall. Stay on guard because there are more soldiers at the end of the hall. Go through decontamination and fight your way down the stairs. The labs should be mostly clear until you reach the last hall and room before Steiner.