List of Donkey Kong Jr. pre-release and unused content

Stage Extra is a stage exclusive to certain prototypes of Coleco Adam version of Donkey Kong Jr.. It is first encountered under the name "Bonus 09", then explored again as "Bonus 12" later in the game.

The stage takes place inside what resembles an old fashioned bakery. At the top of the level, Mario stirs around an active oven, constantly picking up pastry from the oven and trying to drop it onto Donkey Kong Jr., who would have to survive several other obstacles, including automated plungers, in order to reach to Donkey Kong and finish the stage. Each appearance of the stage introduces a new obstacle, such as a dough monster, spawned from Mario's pastry, clinging onto poles and platforms, and a stationary toaster flinging slices of bread at the playable character.

Coleco had planned to include multiple new screens in the Adam versions of both Donkey Kong and Donkey Kong Jr., but Nintendo, not wanting Coleco to take liberties with their games, prevented them from doing so.

Layout
Donkey Kong Jr. starts off at the bottom left. This part features a short tunnel containing four automated plunger-like obstacles, pressed onto the ground. This tunnel leads to a section with a toaster and some hanging poles, the latter which can be climbed to access an upper platform. This platform contains a giant bowl and an automated mixer moving from side to side inside the bowl. Donkey Kong Jr. would first have to simply pass by the huge bowl in the background and then jump onto several other poles in order to climb up to the mixer. It can be stood on just as on a platform and can offer a ride to the following section; by climbing yet another set of poles, Donkey Kong Jr. can reach the top of the stage. Here, he would have to avoid Mario by swinging from several hanging poles. Fruit are scattered in between the poles and can be dropped onto Mario to stun him. Donkey Kong lies caged at the end of the stage, along with a key to release him.