Complete Walkthrough of Secret Level 1 (Smarts)

This is not a difficult level if you know the way to kill the boss.

First head down the door below and kill the P.I.G. to get a super laser boost. You will find that the wall has closed behind you as you fly on. To both the left and the right of the fork is a Smelter. Kill them and you will get an Afterburner and a Headlight boost. (Make sure to turn off your headlights.) Blow up 2 Class 1 Heavy Drillers (they may leave Shield boosts), and kill the Class 2 Platform Robot. Head up and destroy the Mini Boss. Be very careful not to hit any of the windows. (Well, at least, only the "Z" window is important.) Go on (and the wall closes behind again) and kill the Boarshead, getting 2 Smart Missiles. (You may encounter a Smelter with the robot maker texture. It drops bombs and leaves 2 Proximity Bombs power-ups.)

Go on, and destroy the Sidearm (it drops 4 Flash Missiles). Head for the Super Laser boost, and the wall in front will now open. Quickly go back (in case the boss fires Smart Missiles). Shoot up along and you will discover a secret door, revealing 4 Smart Mines. Take it. Now is the key to killing the boss. Just below the Super Laser boost is a secret door. It is locked. Remember this place. Next, as mentioned previously, shoot the "Z" window, and the door will be opened. Afterburn to that door, and you will find an invulnerability inside. Take it, and using Level 6 Quad Super Lasers, go in and fight the boss. There are also 2 Cloaked Diamond Claws and 2 Cloaked Hulks. Destroy them too if you want. By firing cheap missiles (like concussion or homing) and continuous fire, the boss should be dead pretty soon. Grab the 4 Smart Missiles dropped by the boss and power-ups around the boss room.

Look at the lava below, and you will notice a small patch of moving lava. It can be passed through actually. Go in, pick up the Gauss Cannon and 2 Vulcan Ammo. To the right is another illusion wall, containing 4 Smart Mines. Shoot the switch inside. It triggers a door directly above the red door.

Go back to the red door. Along the way there are two previously locked doors opened. Therefore, there are 2 ways to go back to the teleporter:

1) As mentioned previously, the switch opens a door directly above the red door. Enter, take the red key, and helix cannon and some guided missiles (head through the illusion walls). Then, open the red door, and you will see the teleporter.

2) A locked door below near the red door is opened for the boss is destroyed. Inside contains a switch. Blow it, and (being unknown of this walkthrough) go back through the original path down. Walls should open around the previously closed walls, revealing a path to go through the walls. (2 robots per each wall, 4 in total.) Go through the whole path and you will reach the Exit finally.

Well, you could do step 1 first and take step 2 if you like, but that only adds your score (for 300 + 800 + 700 + 1000 = 2800 points) and on higher difficulty levels taking only step 1 is more advisable.

That's it! I will not reveal where Secret Level 2 lies...