At the end of each level if you land on the 7th, 6th, 5th, 4th, 3rd, 2nd, and 1st floors in that order in the bonus jump game, the jump to the 1st floor at the end will reward you with 30 lives instead of 30 Stars.

Start the level and float above the doorway to find something that resembles a window with three bars. Press UP to enter it and play a more difficult version of the level.

Unlock the following bonuses by performing the corresponding tasks:

BONUS - HOW TO UNLOCK
Arena Mode - Complete the game once
Extra mode - Complete the game once
Kirby Master video - Complete both arenas and get %100 on Main and Extra game
Play as any character in Arena - Beat Arena once
Play as any character in True Arena - Beat True Arena once
Sound Test - Complete the game once
True Arena - Complete Extra Mode

In Level 1, Stage 4, head all the way at the end in the first part of the level and walk into the dead end. After that, go all left until you will see a gap. Enter the bush with a black area to find the HAL room. In Level 6, Stage 5, in the 3rd room, go all the way at the end and fly up to the conveyor belts and go into that black area at the top of the conveyor belt. You will go into the cannon room and it will shoot you, and you will see the HAL blocks.

Unlock the following Copy Ability Rooms by performing the corresponding tasks:

ROOM - HOW TO UNLOCK
Copy Ability Room 1 - Collect 20 Energy Spheres.
Copy Ability Room 2 - Collect 40 Energy Spheres.
Copy Ability Room 3 - Collect 60 Energy Spheres.
Copy Ability Room 4 - Collect 80 Energy Spheres.

Unlock the following sub-games by performing the corresponding tasks: These can be accessed aboard the Lor Starcutter, down the ladder after the main lobby:

SUB-GAME - HOW TO UNLOCK
Ninja Dojo - Collect 15 Energy Spheres.
Scope Shot - Collect 30 Energy Spheres.