Huge metroidvania level where you play as Megaman. You must carefully travel through the level and memorize the layout. Some stuff of the level is optional, such as the Bounce Man area.
Guide: You don't start with a weapon but you will get one immediately. Once you find the weapon, either decide to fight the first boss for a extra weapon or go up on the layout. There is a checkpoint room after an area with a press, a cannon and some other enemies, where you can heal. Below the enemies is a weapon required for advancing: the Magnet Beam. Use it to pass over the gap with spikes, which you couldn't pass before if you've been there. You can also use it to unlock the Gemini Laser.
Go up with the platform section and (optionally) grab the extra weapon guarded by a enemy. You can decide to either try to go around the spiky section or fight another boss for some E-Tanks, a key and a new weapon which is required for progression.
Return back to the first checkpoint (where you've found your first weapon) and break the weapon blocks to find another progression item, the Jet Adaptor. Once you get it, return back to the first checkpoint and go up to the checkpoint next to another weapon block. Break it and use the jet to fly past the spikes and fight Shade Man. I forgot what else happens here... but you might have gotten a red key. You can go to the final sections by either a teleporter next to the Noise Crush item or go through the conveyor section, but you'll need another item. Go back where you obtained the Metal Blade and go upwards. Defeat the enemy guarding a M-Tank and fly down (good luck) through the spikes to get the final progression item. After obtaining it, return or optionaly attempt to find a secret item in this area, the Perfect Freeze (which will help alot later). You can now attempt to beat the last section (no returning here!) or try and beat the optional Bounce Man dungeon, which rewards you with the Bounce Ball weapon.
Once you get to the final section, make sure you are well prepared with enough E-Tanks, as the difficulty greatly increases through here. Survive through the enemy swarms and fight another boss while avoiding the incoming lava waves from above (these will instantkill you, so be careful). If you have enough weapons, try to figure the boss weakness.
When you defeat the boss, keep going and try to not die to the enemy and spikes in the next section, and jump to the teleporter.
This teleporter room will make you fight tough bosses, yielding you keys to get past the locked door. Be careful as you will fight multiple bosses through here, and you will have to dodge spikes as you go down one section.
The "last" checkpoint is guarded by a white tiger. Head down the last room while you avoid hazards as you fall down and you will fight two bosses, use Perfect Freeze if you're having trouble.
Finally, once you beat them, you'll end up in a escape section! Be careful around here as you'll die quickly if you wait enough, and you must keep enough health to fight the final boss. TIP: To get through this section easily, slide below the spikes (on the 2nd slide opportunity) and you'll not die from the spike on the floor, as Megaman won't take damage from it. Be careful as a rocket will come from the side so you must wait before sliding. Defeat the two minibosses (beware the cat's fleas!) to take on the final boss. After you defeat it, the victory area is the only last one to finally beat this level. Use every skill you've learned to go up on the tower (be careful of falling down or you'll have to restart from the checkpoint) Reach the room labelled with #1 and you'll have beaten the level!