After Crystal castle [Candle] [Heart] [Heart] [Orb] 
After Plant castle [Heart] [Heart] [Heart] [Space] 
After Rock castle [Heart] [Heart] [Orb] [Space] 
Dracula's castle [Heart] [Orb] [Candle] [Space] 
Dracula's castle part 2 [Heart] [Candle] [Orb] [Orb] 
Dracula's level [Orb] [Heart] [Candle] [Heart] 

Hidden rooms and passages: 

Crystal Castle  -  Climb any rope through the ceiling just past the second door, where eyeballs are falling from above. 

Rock Castle  -  Continue all the way to the right after the third door. Climb the rope up through the ceiling. 

Cloud Castle  -  Reach the room just before the third door. Climb the rope up through the ceiling to warp to an earlier room, where you can find meat in the bricks in the middle of the ceiling. 

Plant Castle  -  Continue to the left after the third door and climb the rope through the ceiling. 

Dracula's Castle (Stage 2)
Climb through the ceiling in the room with a door, a large bat, and an upside down monster that can take away your character's stronger whips.

Crystal Castle  -  Whip the ceiling just above the second door. 

Crystal Castle  -  After the long drop past the spiked walls, whip the ceiling in the middle of the screen with the door. 

Rock Castle  -  It is hidden in a candle above the high ledge, just before the fourth door. 

Plant Castle  -  Whip the ceiling above the third door. Also, in the secret room mentioned earlier, whip the closest floating brick to the right side. 

Dracula's Castle (Stage 1)
After passing through the second door, whip the floor below it.

Gameshark Codes

Description Code 
Infinite Energy 010D89CC 
Infinite Hearts [Note 1] 010988CC 
Infinite Time [Note 1] 010982CC