Complete Walkthrough of Level 1 (Homing and Flash)

First, take the shields on your left and go to the right. Take the Laser and destroy the Class 3 Gopher to get another Laser boost. Next go along the corridor, and destroy the Medium Lifter at the Energy Center. Just before the Energy Center, there is a hidden door below. Open it, destroy the Class 1 Drone and take the Ammo Rack (and possibly an Energy boost).

Go back to the Energy Center, and there will be a Class 1 Driller down there waiting for you. Kill it with a single concussion missile. Grab the Vulcan Cannon, and go up the path. Destroy the Medium Hulk to get 4 concussion missiles. Then kill the Small Hulk and get another Laser boost. (On the way you may meet an IT Droid dropping bombs. Killing it gives you some proximity bombs.)

Continue along and destroy the Super Hulk, and now you're equipped with Homing Missiles. Destroy the Class 1 Platform Robot and you will now have Level 4 Quad Lasers. Go up along the path, and destroy 3 Sidearm Modulas and take the Flash Missiles. The boss lies within the blue door, which is not accessible now yet. Shoot at the left of the blue door, and a secret door should open, containing an invulnerability and 2 Vulcan Ammo. Do not take them now, as they are reserved for fighting the boss.

Now go back down the path again to the beginning. On the way you'll notice robots generated from the weird-looking cube. It is, indeed, a robot generator. Robots generated are Sidearms and LOU Guards. Pick out all the robots and return to the start location. The wall on the left is now opened (previously it contains 2 Shield boosts). You should see a Spreadfire Cannon and a blue key. Grab them.

Behind the blue key is an illusion wall, go in and get a shield. Hit the trigger from outside, and a wall to the right of the blue key will open. Destroy the Class 1 Heavy Driller and get the Plasma Cannon. You have found the secret teleporter to Secret Level 1.

After you have returned from Secret Level 1, now that you have the blue key, it's time to challenge the boss. First try to take out as many robots from the outside as possible. If you're not playing on difficulty Insane, to disable the robot maker permanently, you will have to enter the blue door and exit, and the robot maker will be triggered. Do this 2 times and you will not have to fight the robots when you are on your way to the Exit later.

Take the previously mentioned invulnerability and rush in to kill the boss. If you found the Gauss Cannon on Secret Level 1, use it now. You can increase your firepower with some missiles (preferably concussion missiles for they're cheap). Once you have destroyed the boss, grab the missiles and dash for the Exit. The Exit, had you not noticed by now, is the door behind your start location.

Off you go to challenge Level 2: Mercury Mines!