Press Up, Down, Left, Right, 1 at the first opening screen. Then, press 1 on the next screen. The phrase "Select Round" will appear to confirm correct code entry. Press Start when the desired number appears to begin game play at the corresponding level.
The last eight hostages on level two are in the submarine. Bomb the periscope as it appears from the water. This will cause the entire to emerge. The hostages will appear on the bridge. Land next to them to start the rescue.