Air Fortress/Stage 4

Entrance approach

 * 1) You begin facing two waves of slowly retreating spinning enemies, followed by a wave of Enterprise-shaped enemies.
 * 2) Collect the three energy items below the platform, and then carefully maneuver diagonally up and to the left if you wish to collect the bomb items.  Watch out for the barrier enemies as you collect the next energy item at the bottom.
 * 3) Two sets of Wave enemies will appear next, first in short wave formation, and the next in a longer wave.
 * 4) A new enemy type will appear, wedge ships which start off slow but gain speed and accuracy as they approach.
 * 5) Destroy the barrier before an energy item, then take out the hatch enemies.  Before collecting the next energy item, watch out for the fast rotating cubes.
 * 6) Lug-wrench enemies are followed by two barriers before a set of hatch enemies.
 * 7) Fast retreating circles appear while two energy items show up near the top.  Scatter these enemies away before the spray the screen with bullets.
 * 8) Enterprise-shaped enemies show up just before a set of items appear.  Collect these items from bottom to top, but be careful when you go after the bomb item at the top.  Fast retreating enemies appear, but if you're stuck at the top, you can't chase them away and they will fire on you before they leave.  Once they are gone, you will land in front of the entrance.

Fortress interior

 * 1) The elevators in this fortress go between more than just two levels.  When you arrive, don't depart to the left.  Instead, head one floor lower.
 * 2) * In preparation for your escape, you may wish to go two floors lower and destroy the two mini-cores you find before the passage dead-ends. Then return to the left and ride the elevator back up one floor.
 * 3) Exit the elevator and destroy the two blue robots you encounter before heading left.  Destroy as many enemies as you can as you proceed to the left.  Destroy the mini-core that you come to, and continue on to the left.  Watch out for the flame spraying orb before the elevator.
 * 4) Ride the elevator up to the top, and proceed to the right.  Take out the mini-core along with the robots that you find beyond it, and fly up chute A.
 * 5) Chute A will deliver you right to the fortress core.  Remove the two robots and destroy the core.  Then fly back up the chute which is now chute C.
 * 6) Chute C will deposit you at the dead-end side of the bottom floor of the elevator that you arrived in the fortress from.  If you did not visit this early, you will have to destroy the two mini-cores as you make your way back to the elevator on the right.
 * 7) Ride the elevator up one floor and pass through the same corridor that you did the last time to the elevator on the far left side.  When you reach the elevator, take it down two floors.
 * 8) Because of the time it takes to reach this point, the fortress will begin to shake, but don't worry, you still have plenty of time.  As you move to the right however, you will encounter two more clones.  Hit them with a bomb to remove them as quickly as possible and continue to the elevator on the right side.  In a worst case scenario, simply avoid them entirely; do not get caught up in a battle with them.
 * 9) After taking the elevator down, fly down and around to the right, taking out the robots as you go, but do not stall.  If the lights begin to shimmer, you are running out of time.  Take the elevator on the far end up to the next room where the escape Lightspeeder is waiting.