Complete Walkthrough of Secret Level 3 (?????)

==You can start from this level without missing stuff from previous level(s) if you can access the secret level.==

Well, this level is straightforward. It is simply a warehouse to give you anything that you can grab. Just keep grabbing all the stuff you can access and stop only until you see some Smart Missiles.

Now, above you is a Phoenix Cannon, and to your sides are the Helix Cannon and the Gauss Cannon. The switch in opening these walls is just on the floor of the upper left corner of the Phoenix Cannon. So how do you shoot it? There are 3 methods:

1) The easier method. Shoot Smart Missiles at the ceiling of that corner and hope its plasma bomblets hit the switch. This method is easy to use but it wastes vital Smart Missiles that should be kept for fighting the boss in case you should run out of Earthshakers.

2) The much harder and time-wasting method. Take the 4 Smart Mines below, and fly towards the grate with the Phoenix Cannon, immediately dropping a Smart Mine. The momentum should carry the mine inside the grate, and using Concussion Missiles, get the mine to that switch with missile explosions. This method does not waste missiles used to fight the boss and the advantage is that the mine will be nearer the switch and increases the chance of hitting the switch.

3) The third, is of course, that you already have the Phoenix Cannon from the previous levels and you can simply shoot the switch without any problems.

Once you have got your Phoenix Cannon, proceed. Fly till you see the Omega Cannon above you. An identical switch trick. This time you can use your new Phoenix Cannon to shoot that switch, of course. This switch opens all the walls you have met so far (except for the Gauss, Helix and the Phoenix Cannons), so go back to take the Super Lasers and Guided Missiles.

Proceed until you reach the hall with 8 Earthshakers. You cannot access them yet. Shoot above you, and you should discover that the ceiling is an illusion. (If you cannot differentiate which is the ceiling, simply shoot the middle walls of the four directions and one of them can be shot-through.) Fire a Guided Missile there, and to the end of the corridor (you will need to make some sharp turns), and hit the switch. The wall below you has opened, and you can go in to take the Earthshakers (WOW!).

Before destroying the reactor, you must locate the Exit. Assuming that the reactor is below, the Exit is located behind an illusion wall to the left of the ceiling. Blow up the reactor, and go there. You may discover that you have not been sent out of this mine yet. Don't panic, for the real exit is the secret teleporter above inside the Exit.

Good luck with the final boss!