Door

"I'd suggest making a note of which doors you go through as you explore."

- Daroach

Doors are portals that allow Kirby to move from one area to another. In most cases, they are black arches with stars along the top. In Kirby's Adventure, doors do not have any stars around them except for the final door in each level. In Kirby & The Amazing Mirror, they are replaced by Mirror Doors, which act exactly like a regular door, but look like mirrors and sometimes lead Kirby to different worlds. An enemy, Mirra, is sometimes seen around a Mirror Door, and must be defeated before Kirby can enter. Sometimes, both types of doors are hidden by Star Blocks, and other times Kirby needs to pound a stake to break down walls and reveal doors.

In Kirby: Canvas Curse, doors are slightly bigger relative to Kirby and have more stars. The final door is replaced by a rainbow canvas that warps Kirby out of the dimension upon contact. A door is also drawn in Paint Panic.

In most games, the player must press up to enter a door. In all touch screen-based games (Kirby: Canvas Curse, Kirby Mass Attack, and Kirby and the Rainbow Curse), Kirby enters the door automatically.

Usually, certain doors look different than others in the same game, which often denotes a different type of area. For example, in Kirby's Return to Dream Land, doors with orange stars above them lead to secret rooms or even different routes that contain more bonuses than the regular path. Doors simply leading through the levels have the traditional yellow star. Additionally, the final door in each level that serves as its exit looks different; it is much larger with a rainbow aura. Interestingly, Kirby can carry items, like keys, through doors.

Moon
The Moon is a recurring secret door appearing in Kirby games. It usually appears as a crescent moon high in the night sky.

So far, it has appeared in Kirby's Dream Land, Kirby's Adventure, Kirby Super Star, Kirby: Nightmare in Dream Land, Kirby Super Star Ultra, Kirby's Return to Dream Land, and Kirby: Triple Deluxe. Most of the time, it is a simple Easter egg. In some games, however, it is mandatory to achieve 100%.

Kirby's Dream Land
The moon makes its first appearance in the Bubbly Clouds stage of Kirby's Dream Land. After entering the moon, Kirby is falling, along with three Maxim Tomatoes and two 1UPs. It's not possible to collect all of the items, however. At the very bottom is a door leading to Kracko.

The moon is still available to enter in the Extra Mode. Here, there are only two Maxim Tomatoes and a 1UP, along with a massive amount of Gordos. They are easy to avoid, however.

Kirby's Adventure and Kirby: Nightmare in Dream Land
Stage 6 of Rainbow Resort is a homage of Kirby's Dream Land. One of the segments is from Bubbly Clouds. This segment still has the moon, in which, upon being entered, leads Kirby to the last Switch, as well as supplying him with a Maxim Tomato and a 1UP. The moon in the Extra Mode and Meta Knightmare remains unchanged.

Kirby Super Star and Kirby Super Star Ultra
Spring Breeze is a Sub-game based off of Kirby's Dream Land. Bubbly Clouds is still a stage and the moon can still be entered; just watch out for the falling Grizzo. Kirby will fall as usual, but there are no Maxim Tomatoes, but food scattered everywhere. There are four clusters of grapes, five pieces of meat, four peaches, and a 1UP at the far right. At the bottom is the door leading to Kracko, but Kirby will also come across a Noddy and Bonkers, which the player may choose to fight. Should the player float out of view of of the Noddy and Bonkers, they will respawn. The moon in Meta Knightmare Ultra remains unchanged.

In Kirby Super Star Ultra, the moon also appears in the new sub-game, Revenge of the King. Here it appears in Crash Clouds. The grapes are replaced with bananas, the meat is replaced with soda, and the peaches are replaced with meat. The locations of the food and 1UP remain the same, however. At the bottom is another Noddy and another Mid-boss, Grand Wheelie. This fight is not optional if Kirby enters the moon. Upon defeating Grand Wheelie, Kirby may then proceed to exit and fight Kracko's Revenge. Floating out of view of Noddy and Grand Wheelie will not cause Grand Wheelie to respawn, but Noddy will respawn like most enemies.

Kirby's Return to Dream Land
In stage 7 of Dangerous Dinner, Kirby should ride the Warp Star to the exit door, but instead of entering the door, float above it to the planetoid in the background. Kirby can enter this planetoid like the moon. Kirby will spawn on a platform. He can fall from the platform and collect up to 100 Stars, a pair of cherries, a cake, an ice cream cone, meat, a Maxim Tomato, and a 1UP. Two flowers also appear at the bottom.

Kirby: Triple Deluxe
The moon makes its appearance in Royal Road. In stage 1 of Royal Road, Kirby will fight against Gigant Edge in the wind. Upon defeating Gigant Edge, Kirby can skip the door that appeared and continue to the right. After floating up, Kirby can collect some items. In the background is the moon. Entering the moon will lead Kirby into the second HAL Room.

The moon also appears in stage 8 of Royal Road. In the last room, Hypernova Kirby reveals a timeline showing his various appearances. At the very end, Kirby is found with King Dedede on Bubble Clouds. To the left is the last Sun Stone representing the sun, and to the right is the moon. Kirby can skip the exit door again and enter the moon. Entering the moon will lead to a room of similar theme to Fine Fields, in which the Cookie Country music plays. Kirby may fall and collect the following: cherries, a pineapple, bananas, a peach, a watermelon, acorn squash, a carrot, lemonade, a cake, a cake slice, an ice cream cone, a sandwich, a red star, a donut, flan, a chocolate bar, omurice, another red star, curry, bread, a hamburger, pizza, meat, three 1UPs, a Rare Keychain (Taranza), two normal Keychains, and two blue stars.