You will start outside the castle. Head right and kill the two ravens you come across, then use the floating platform to get over the bottomless pit.

Once you get off this platform, head right to find a new enemy: Zeldo. These cloaked figures will throw scythes at you, which act like a boomerang. They will sometimes duck before they throw them so be ready to jump or duck their attack depending on what they do. They take several hits to kill, especially if you haven't got the whip upgraded. Once the Zeldo is dead, head right and use another floating platform to get over another bottomless pit. Then head right and deal with the raven and Zeldo waiting for you. After those are dealt with, keep going right and kill the other ravens you come across.

Once the ravens are dead, go through the door to finally enter the castle. The first room has a single vampire bat it in along with two floating platforms, all of which are located over a floor of spikes. Dropping onto the spikes will do a lot of damage, so jump on the first platform and let it take you up, so you can kill the bat easily. Then jump over to the next platform and then go up the rope. The next room has some extending spikes, so time your jump to land on the top spike and then quickly walk to the left. Then use the rope in the upper left to get out of this room.

The next room is similar to the previous one, but has a floating platform and a vampire bat in it. I'd advise killing the bat first, then jump on the first or second extending spike to make your way across to the right. Head up the rope and enter the next room, where you need to immediately jump on the floating platform. Time your jump so you will land on the extending spike that bursts out, then get on the ledge on the upper left and use the rope to exit the room. The next room has a Zeldo and a punaguchi in it, take out the Zeldo first and try to avoid or destroy the punaguchi's attacks. Once the Zeldo is dead, kill the punaguchi, then use the extending spike to get to the ledge on the left. Then use the rope in the upper left to exit.

When you arrive in the next room, there are two big bats to kill, once they're dead go through the door at the right. You'll then be in a room with a small spike pit and a punaguchi in it, use the floating platform to get close enough to the punaguchi to kill it, then jump off and head down the rope. When you drop into the next room, jump over the tiny spike pit and then start making your way down the ropes, taking out the rope skeletons that appear along the way.

Throughout this room there are several small spike puts, so don't leap before you look. Continue downwards and kill the evil knights you find, there is also another big bat to deal with. Once you get to the very bottom, use the rope in the lower right corner to get out of this room.

In the next room, immediately kill the punaguchi and then wait. You need to try and grab onto the rope on the bottom left, and there are two ways of doing this. You can either use the platforms to get across, but then you need to time your jumps to avoid the extending spikes on the upper left. The other way is to jump onto the shooting spikes, and then let yourself fall down onto the bottom floating platform when they retract. Once you've done this, head down and into a small room with a big bat in it. Kill it and then go through the door. You've then got a choice of going up or down the rope: