Great Escape, The Cheats

Once you are in third level pick up the sniper rifle, stick grenades,
keys and other ammo in the store room by entering into it from the top.
You can reach to top by using ladder on back side of building.
After you have collected the ammo again go on the roof. Lay down behind
the wooden block and first hit the searchlight guard. By doing this you
won't come in notice of the officer and other guards. If by any chance
you are noticed select the Lugar Pistol and blow up the guard in one
shot by hitting them on head.
 
If you some how go on low Ammo try searching it near dead guards. If an
enemy is behind an oil barrel hit the oil barrel which will kill the
guards behind it.
To Kill Guards Easily In Segvicks Level
Once you have got the vehicle run your vehicle  over the guards in the
way. This will save you from damage and will kill opponents easily.

While you are driving the tank, you encounter another tank. You cannot fight; park somewhere safe and run into the house with the stairs. Go to one of the levers and pull it. You will see a train appear and hit the tank, clearing the path for you.

During missions, you can only save a certain number
of times. The amount of saves you get depends on the mission.
Make sure to only save after you clear a major obstacle or objective.
If you save too much, it will not let you save anymore and this
can cause trouble if you get caught frequently.
Trainer: All levels unlocked by PiZZA
Trainer: +3 by PiZZA

While you are driving the tank, you encounter another tank. You cannot fight; park somewhere safe and run into the house with the stairs. Go to one of the levers and pull it. You will see a train appear and hit the tank, clearing the path for you.

Beat the game once to unlock The Greatest Escape Mode.