This level can be difficult to pass if you have no sort of pattern for getting through, because, as the title implies, you'll have enormous rockets fired at you from the right - seriously, I'm talking huge. There are only two ways to dodge them, which come in the form of heads in Headcases across the level. You can either grab the Pin Head and hide in the holes in the ground, or (if your feeling daring) grab the Spike Head and stick to the ceiling as the rocket flies past, allowing you to grab some points. Personally, I use the Pin Head, so I'll be going through that brief strategy first.
As soon as you enter the level, you'll spot Headcase, so quickly grab the Pin Head and jump into the nearest hole. The rocket fire will be signaled by the flashing of some arrows, and a siren. As soon as it's passed you, jump out and run as fast as you can to the next hole before the next rocket fire - now just keep repeating that till the end. When an enemy is in your way, you can save time by jumping when you hit it, and this way, you won't have to stop running. I find that, when I make the final run to the end of the level with the Pin Head equipped, I always get hit by a rocket - I don't know whether it's me, but just be ready to get hit at that point.
Now for the Spike Head. First of all, I must remind you that the Spike Head doesn't last forever, so be sure to grab it again whenever the opportunity presents itself. You dodge the rocket by constantly banging your head on the ceiling, but not just randomly. Grab the ceiling whenever you begin to fall, and you should stay just above the rocket. Don't be tricked by the ceilings which appear to be high, but on closer inspection, are in fact slightly lower, because this can bring you down into the path of the rocket. Finally, be sure to grab the Jellybean at the end to regain any lost health.
More enormous rockets here, except now you've found the source, and need to take it down. Begin by grabbing a Pin Head from Headcase, and walk into the hole. As soon as you do so, the screen will scroll to the right, and the rocket fire siren will go off. After the rocket has passed (at which point, you should be in the hole), one of two things will happen:
1. the siren will go off instantly, or
2. you'll have a few seconds before it does.
Either way, jump out of the hole and hit the Missile Man from a distance (this is an important detail to remember, as getting too close wastes time - there's a perfect spot, between two bricks, where you can hit him from). If scenario 1 occurs, you'll only have time to hit him once, before rushing back to the hole. Scenario 2 will allow you to hit him 4 times before returning. Once he's defeated, the whole place will explode, and the way to the next level will open up.
If you want to beat the Missile Man with the Spike Head, then simply follow my strategy from the last level about dodging rockets with the Spike Head - it's a lot easier in this level since the Hangman is at hand when you need another Spike Head (though the Missile Man can be defeated before this is necessary).
To begin, hit the penguin in front when it's standing on the blue blocks. He'll freeze, and cause the blocks to collapse. Go down, and hit the next penguin in the same way, being careful of the guy in the chair who will drop something on you. To get the jellybean behind him, get right up to the wall he's on so he'll stop firing, and hit him till he explodes.
When you go down the next hole watch out for some spikes. Then, drop down a third hole into an area with a funny blue pillar thing cornering you. If he squashes you, then you're dead. So hit his head - being very careful not to hit his body - to create a step for you to reach. Once on his head, let him take you to the high-up ledge leading to the next funny blue pillar thing. After that, travel right, into a large room where Tarot will appear with objects flying around him. Two of them are Headcase and Hangman (whom is to be avoided), and the others hold the key to defeating Tarot in his first stage. The bronze, numbered orbs must be bashed into him to cause damage - the higher the number, the higher the damage done. Beware of the heart orb, because hitting Tarot with this restores his health.
After Tarot's mask comes off, he'll start swirling his spikes on a chain, further and further out. At first, the spikes won't get in the way of you hitting his face, but once they're further out, you'll have to sequence it so that you go in to hit him when the spikes are moving away from you. Eventually, the spike will come out far enough to roll on the ground, so be prepared to jump over it. Once Tarot is beaten, for some reason you have to stand next to his head on the ground before it can explode (this could just be a glitch in my game).
Next, you'll need to grab the Spike Head (after getting any needed sleep with the Sleepy Head), and go back to the hole in the ceiling so you can stick to the wall and make your way up, making sure that the spinning buzz-saws are destroyed first. Once you're up, watch out for the Venus Headdy Traps, which can take your head and turn it against you. Defeat them by ducking and hitting the plant pot while the plant's head is raised. After a few Venus Headdy Traps, you'll approach a cliff edge. Drop down, and if your aim is true, you'll land on a scarecrow, and not on the spikes. Make your way to the right, jumping from scarecrow to scarecrow, until you reach the last one, with no choice but to use the Hangmen above that keep coming and going. Get your timing just right so that you can grab each head one after the other, and lunge yourself onto the upper ledge, leading you to the next level.
In this level, you have to flip the room, by hitting the flying blue things, in order to proceed. When you do this, certain things in the room change, as you will see. For example, there's a guy in a rowboat who rows back and forth, and flipping the room traps him underneath his own boat. There's also another enemy who shoots at you when he hangs on the ceiling, but remains still when you're on the floor - you can destroy the things he fires at you.
At one point, you'll come to a bunch of blocks with people inside, which are essential for crossing the spikes. So, put the spikes on the ceiling, and position the blocks underneath them. When you flip the room back, you should be able to cross over to the spikes (watch out for one of those enemies hanging from the ceiling). After doing this once more, there'll be yet more blocks, and a small puzzle to solve - you have to pile two blocks on top of each other in order to get through the door when it's open. So begin by pushing two of the blocks right next to each other against the wall, and flip the room. Hopefully, one of the two blocks will fall into a hole in the floor, and you'll be able to push the third block on top of it. Then flip the room once again, and you'll have a tower high enough for you to reach the upper ledge.
Next up, you'll be fighting Sparky, so restore health with the Sleepy Head from Hangman, and then grab the Empty Head so you won't get hurt for at least half a minute. When you enter, three different sized balls will fall from the ceiling. Whenever these balls do move around, they're lethal, so avoid them (when the Empty Head has been used up). Sparky will attack by powering up a bolt of lightning and firing at the floor below. Your aim is to hit him with the balls (which do equal damage despite their size), and this is done by luring him over to one of the balls, and as soon as he's floating over it, flip the room and the ball will fall from above and hit him on the head. If your lucky, you'll have two balls lying side by side, meaning that you can hit him twice in one go. Keep in mind that as soon as you flip the room, he'll already be floating in your direction.
Once he's defeated, make sure the Dark Demon portraits on the wall are the right way up in order to proceed to the next level.
This is probably the hardest boss in the entire game. If you defeat this, then I think you can call yourself a real gamer (getting up to this point, alone, is quite an achievement in itself). This is how Twin Freaks works:
His head will begin as a cheerful (referring to his face) green, and when it is green, he is moving slowly, and you can damage him by hitting the ears. He'll also shoot mini heads out of his ears. Bean Head comes out of his right ear, and homes in on you. Money Head comes out of the left ear, and flies across the screen, bobbing up and down. Either of these can be destroyed with a single hit (Bino can also appear randomly to give you a Secret Bonus Point). If you flip the screen, then Twin Freaks becomes a much angrier red, and charges towards you, so just run (don't bother trying to damage him, as you can't, anyway)! All mini heads disappear when his head is red, and you can sometimes use this to your advantage.
Generally, the terrain is easier to cross when the head is red. Speaking of which, there will be a point, just after you make him red, where you'll see Headcase. Hit him as soon as he's visible to get the Slammer Head - this will cause twice as much damage to the boss.
Just one more point - I would advise trying to keep the boss's head green as often as possible. This means not flipping the room to the red head, unless it's absolutely necessary.
One reason why this boss is so hard is that if you get squashed, you die instantly. So avoid that, on top of the Money Heads, Bean Heads, spikes, etc.