Spanky's Quest

Start in the password section, use 000 as the code and press start to begin playing.

.done once you beat boss 3, at the end of world 3.

You start with 3 lives, getting hit removes a life and any hats you're wearing and gives you temporary invincibility, once you run out of lives you start from stage 1 in the current world(1-1, 2-1, 3-1). You also lose any stored keys.

Unclear mechanics
Some blocks(but not brick walls) can be destroyed by touching them with a bubble, this can reveal secret doors, hats, or coins/lives.

Secret doors are free to enter, and give free lives if you beat the minigame. After you win or fail the minigame a door will show up letting you go to the next level, the doors are free with no keys, 1 cost with 1-3 keys in inventory, and will cost enough to bring you to 3 keys if you are above 3. Using these lets you bring extra keys to other levels.

Damage done by balls is determined by time on target.

Grabbing a item with a bubble with automatically upgrade it to basketballs, keys will always fly to spanky when grabbed in a bubble and popped.

Some jump pads can give you extra lives if you throw a bubble into them.

Hats
Spikey hat - lets you run into 1 enemy and they die, but you lose the hat.
Top hat - Basketball bubble in a single bounce.
Baseball cap - Bubbles attract to Spanky's head.
Winged Circlet - Move Faster, walk on ice freely.
Strawhat - Lets you float by holding the jump button.