If you pause the game you will discover that you can still aim the cross-hair. Now you can position the crosshair over the motionless bodies, then unpause the game and let `em have it.

• Shoot as many of the buildings as you can, as they block your shots at attacking / hiding enemies.
• Shoot the enemies at the bottom of the screen as the bullets they fire need less time to get to you and can often trap you in a corner.
• Don't forget that you can shoot the enemies' bullets!
• Try to pick up the bonuses straight away. The 100, 200 and 300 point bonuses are very useful if you want extra lives.
• Collect special weapons straight away as their rapid fire removes buildings faster, giving more breathing space.
• The grey uniformed soldiers (the ones that take a few shots to kill) can give a grenade or a special weapon. When he does, two men carrying a stretcher will appear. Shoot these and they will give you two grenades, collect them and then shoot them again before they go, to receive two more grenades.
• Never stay in corners for too long, the enemy have a habit of zeroing in on you.
• Don't waste grenades on buildings unless you really need to. If you opt to shoot in small bursts at every building rather than concentrating on one building at a time then a grenade may finish the job a lot quicker.
• Try not to get killed when the end-level guardians appear, otherwise your FOE meter will drop to zero and you'll have to start again.