You need to destroy the bridge. But first you need to find the store room.
Walk to the left and look at the map to get an idea of the area. Leave the map and walk further to the left. Pick up the SILVER coins from the floor. Find the cave blocked with a huge boulder. Next to it is a device which asks for a code. Use the fluff from your pocket on boulder and the protector will stop working, removing the boulder. Walk into the cave on the left and pick up the GEMS, the CAKE and the SWORD.
Leave the cave and walk to the right until you find a guard. Talk to him and ask to pass. He won’t let you. Ask if takes bribes and he not unwilling. Give him the gems and you can go further. But there’s another guard. Talk to him to find out his gun isn’t real. But he won’t let you pass either. Give him the cake and you can go further to the right.
There’s a gap in the bridge but when you walk further you’ll fall down but can still continue your quest. Walk to the right into the tunnel and talk to the dealer. Ask what’s for sale and he’ll tell you about the special bombs. Give him the silver coins and buy the plunger… there’s no other way. Leave to the left and climb the ladder.
Walk to the left and find a PICK AXE under the bridge. Pick it up and walk back to the right. Climb the ladder twice and receive your next assignment: get the bomb programmed. Walk to the right and find a huge rock blocking your way. Use the pick axe to break away the boulder and climb down the ladder.
Talk to the scientist on the left to get your plunger programmed. Then go up the ladder again and walk to the left. Climb up the next ladder to reach the top of the bridge. Walk to the right and enter the building. Talk to the man and he’ll tell you what he did. Use your sword to kill him and then pick up the GUN. Leave the shop. [NOTE: Due to a bug, you can’t walk anymore but you can ‘use’ the exit, just above the mouse-over text.]
Walk to the left and walk across the bridge to the left. Since you’ve got a gun, you can shoot the guard there and place your bomb on the weak spot. Then run for your life. And although you’re captured by the Americans, your mission is complete.
Game source: A copy of the game was found here on the internet.