Please help me...
I am a prisoner in the dungeon of the castle. My name is Zelda..."
With these fateful words, your quest to save Hyrule from utter destruction begins.
Zelda is being held prisoner by a wizard named Agahnim, who has taken the castle by force. Other missing girls have fallen prey to the wizard's dark magic. Agahnim plans to break the legendary seal of the seven wise men, which will spread untold evil across the land.
Your uncle awakens you to say he'll be back by morning, with an order not to leave the house. Bearing a sword and shield, he leaves.
You have no choice; you must go against your uncle's orders and attempt to rescue Zelda.
Open the chest in the corner (press A in front of it) to get the Lamp. (If you don't get it now, you have two more opportunities to get it.) The lamp lights up dark rooms automatically. It can also let out a small flame to light torches; this requires magic, which you do not yet have, but will obtain later.
Lift and throw the pots by the bed (by pressing A) for hearts, though you don't need them at the moment. Remember that your house will always have three hearts in it, if you are low on health.
Leave the house and walk out into the pouring rain. You can pick up bushes with A; some of them might hide rupees. You will want to collect rupees whenever you can, so you can buy important items to aid you in your quest.
But how do you get into the castle? It's certainly heavily guarded... If you wait long enough, Zelda will contact you again to tell you of a secret passage somewhere near the castle.
Go around the back of your house and walk off the back ledge, then exit north. Above you, a little to the left, there is a bridge leading up, go up it and you see a soldier in gold armor with a large shield guarding the gated castle entrance.
Now to find the secret passage Zelda spoke of. Go east from the soldier along a path on the inside of the moat. To your right there is a large, white boulder that you cannot lift. Go north. At the end of the path is a bush with a stone border around it. Lift it to reveal a hole.
Be brave and step into the hole. You land in a shallow pool of water.
Head left to find your uncle, mortally injured. He gives you his sword and shield and tells you how to focus power in your blade (hold B) then release it. This is the spin attack. Hold B until your blade charges up, then let go and you'll spin the blade around you in a circle, hurting whatever enemy is close.
Press B to swing your sword at enemies. You will be doing that for most of the game.
Go left and down through the door. Head right and there are some soldiers in green armor with small swords patrolling the hall. Use your sword with B to kill them; they are surely controlled by Agahnim. They may leave behind hearts or rupees when defeated.
Continue right and you see a chest with a blue rupee inside (that's worth 5), unless you didn't get the lamp in your house, in which case the chest will hold the lamp. Be sure to lift the pots for a couple of small magic jars. Be careful not to press Y; that will use the lamp and thus use some of your magic. You want to save your magic for when you need it. There is a torch in the bottom left corner that you can light with your lamp, but don't be tempted to light it; you can see well enough in this room, so it would just waste magic.
Head left again and go up the stairs and through the door to get to the castle courtyard.
Cut down the bushes with your sword, and start heading left and down until you're past the pink barrier. Get rid of the bushes just below the barrier, but be careful, the green soldier with the big sword will come charging at you when it notices you. Your sword will bounce off of his if you aren't in a good position to hit him. Get rid of any soldiers in your way and go through the door above you.
In the castle, go up, then head through the door to the right. Follow the carpet to a door in the north wall, fighting the green soldier on the way. In the next narrow hallway, there are three green soldiers, one with a big sword. Get them out of your way, and continue on through the next door.
Continue west until you see some stairs going down; go down them. You see a blue soldier with a big sword; kill it and it drops a small key; pick it up. Open the chest here to get the dungeon map! Press X to view it. Go through the locked door below.
In the next room you have to be careful, there is a bottomless (or so it seems) pit all around and you don't want to fall in. If you do, you lose a heart (or less) and reappear somewhere on the screen.
There is a soldier wandering around on the floor below you. You can wait until it's near the edge, then jump off the ledge and land behind it and hit it with your sword, knocking it into the bottomless pit! Exit south.
There are two soldiers here, and two pots. Along with knocking them off the ledge, you can also kill the soldiers by throwing a pot at them. Most enemies will be hurt or killed if you throw a pot or other object at them.
Below is another pot, this one containing a heart, and there is another soldier here. Kill it and follow the path to the next screen.
To avoid the green soldiers here, go up the stairs you see and down the narrow path to another set of stairs to the left. From there it's a straight shot up to the next room, and you can avoid the soldiers entirely.
In here, you must defeat the green soldier for the doors to open, so do it. Go through the door to the right.
There are statues all around and a blue soldier. Kill it to get a key, then open the chest for the boomerang! Press start and switch to the boomerang now, to make sure you don't accidentally waste magic by pressing Y with the lamp equipped. The boomerang can stun enemies, as well as grab items that are far away, like hearts or magic jars. Now leave this small room.
Go up the stairs and through the locked door. Follow the path until you get to the jail. Defeat the green soldier. If your hearts are full, don't open the chests above. If you're in need of hearts, however, get one or two of the pots to fill them. You'll want to try to save those pots in case you need them after fighting the next soldier.
East from the first jail cell you see a cell containing Princess Zelda! But guarding her cell is a soldier wielding a ball and chain! Your strategy is to run in close and hit it, then run away fast before it spins its ball and chain. You know it's about to spin it when it stops moving for a second, so don't get close if it stops for very long. If you lose hearts while fighting it, get some from the pots in the cell.
Once you defeat this bad guy, you win the big key! With it, unlock Zelda's cell and she'll talk to you, warning you that the wizard is controlling the castle soldiers with magic, and has done something to the king. She asks if you understand, and if you want her to repeat what she said, say no. Otherwise say yes and she'll continue. She knows a secret path out of the castle, but you need to get to the first floor first.
Open the chest next to the Princess for 5 rupees (or the lamp if you STILL didn't get it) and head back the way you came.