Mickey Mousecapade/The Castle

Note: this stage is named Queens Palace in the Japanese version.

Objective
You have made it to the final stage of the game. Like the very first stage, you must find and collect a key that will grant you access to the door to the final boss of the game. In addition to the boss fight, there are some tough fights with a Walrus, and a reprise visit from the boss of the previous stage! Keep your health up as much as possible, the enemies are at they most relentless.

Details

 * A: Your first goal is the key which you need in order to reach the final boss. Without this key, you may make it all the way to the door, only to find that you are stuck.  So head here first and collect the key.  Minnie may not have an easy time following you here, but you only need to collect the key and return the way you came, so it's OK.
 * B: Entering this portion is completely optional, and not recommended if you already have a good supply of extra lives at hand. You'll have to fight with the Walrus who is a tough customer to beat, in order to get a clear shot at the space above his head, which contains an extra life.
 * C: Just when you thought you had pushed this boss down in the previous stage, he's back with a vengeance. Do your best to take him out while taking as little damage as possible.  It's not a bad strategy to leave and re-enter the previous room, and shoot the hidden item locations in hopes of discovering an invincibility fairy.  Then you can simply crash into him and be on your way to the real boss.
 * D: If you collected the key, you will be able to open the door here, but not until you put down the Walrus that is guarding it. Undoubtedly, the fight with the Walrus will take away some of your health, so it's best to leave and re-enter this room over and over again until a hidden item location reveals a health refill, or even better, an invincibility fairy.

The final boss
Whether you're up against Maleficant the Wicked Witch, or the insane Queen of Hearts, you have your work cut out for you. If you went to the trouble of finding an invincibility fairy before you arrived here, rush the boss as quickly as you can because the fairy will start to depart as soon as you arrive. If not, you will have little choice but to get in real close and start wailing away with the projectiles. This boss fires endless waves of bouncing projectiles at you with little rest between volleys, so you have to get beyond them and pelt the boss with shots of your own. If you entered with sufficient health, you should be able to defeat the boss well before she has a chance of stripping you of all your energy. Then you will pass through the door beyond you and rescue the familiar Disney character waiting on the other side.

Note that if you happen to be defeated while fighting against this boss, you will have the misfortune of finding yourself back on the other side of the doors present in the room where you first got the key (point A), and must retrace your steps to get all the way back to the last boss. For this reason, it is vital that you not enter the fight unless you have a fairy or full health.