Aim and shoot. It’s so easy and fun. Why? Because the obstacles are new all the time and the same thing can be said about civilians and enemies. It’s not only about good shooting but you must be quick.
Longs story short – you have to shoot everyone in every level. You are hidden behind and concrete tree and jump out in the right intervals to shoot. From boxes you can get grenades or health. Watch out for the civilians, they mustn’t be hit.