The Hunter base is under attack! The game starts with a cutscene showing X and Zero taking down a large insect-like flying mechanioid. They land outside of the base and Zero says he'll take care of the enemies outside while X heads inside.
Hunter Base[edit]
After the cutscene finishes, head into the Hunter base. You'll immediately run into a Notor Banger. You can take it out with a few shots. Jump at the wall behind it and wall jump up. You'll see several more as you continue through the room.
At the end is a Caterkiller guarding a health pickup and a ladder down to the next room. Careful with the Caterkiller as it's attack works as a barrier for it as it is charging it up, and will then try to aim it to fire at you. The two shots can fire straight if fired from the center, and further apart in rotation as it has to aim higher or lower. You can kill it before it starts charging its shot, or after it fires it. The projectiles will return to the Caterkiller and it will begin to charge another attack towards you if you take too long. If you are dashing, you should be able to reach the ladder before it fires any shots.
Down the ladder is another Caterkiller trying to block you from running off the edge, try to drop towards the right side of the gap quickly before it can finish charging its attack. You can just blow throw more Notor Bangers on the floor as you dash through the rest of this room. You'll find another ladder down to another room.
When you continue on you'll run into another Maverick Hunter, Mac. However, he's turned Maverick and traps X. He'll use a Hangerter to drag X away and disappear. Then Zero will drop from the ceiling and you'll take control of him. You'll notice he has much more health than X, and if you try charging your buster you'll see he has several charge levels allowing him to fire two shots and use his z-saber at the higher charge levels.
Continue through the room watching out for parts of the ceiling falling down trying to damage you, Earth Commanders that may fly in a circle around the screen, and a few Head Gunner customers firing at you. Keep heading forward and you'll find a ladder up out of the room.
Don't fall into the pit in the next room, and start climbing up the wall. Spiked balls will start falling down towards you, you can try to avoid them by dash jumping to the opposite side after each one, or you can just tank a few hits as they don't do much damage. At the top you'll see that it was a Ganseki Carrier droping them down on you. Try to avoid the one it's currently holding and about to hurl at you, and it will fly away. After this is a shutter.
Mini-Boss: Mac[edit]
Mac isn't particularly powerful. Avoid him jumping at you at the beginning of the battle and try to stay towards the opposite wall from him. His attacks include a rapid shot, a jumping rapid shot, and a single large shot. You can avoid them by wall jumping, but the rapid shots do track you. It should only take a couple charge shots or so to defeat Mac.
Afterwards you can shoot the Hangerter holding X. After a short cutscene, you'll take control of X once again. There's not much stage left, the shutter leads to a wall you need to climb up, and another shutter to the boss.
Boss: Maoh the Giant[edit]
Being an intro stage boss, the difficulty of this boss fight is almost nothing. He'll probably get a cheap shot on you at first, but if you stay between his mace-like arms and face back and forth left and right you shouldn't get hit since his arms aim towards where you're going to be, not where you are. Just keep doing this and charging your buster to shoot his face several times and you should quickly kill him. After another short cutscene you'll finish the stage, get your password, and be on the stage select screen.