Cloning refers to a number of glitches that allow Mario to hold objects that were not intended to be held. Typically, this happens when Mario continues to hold an object slot after the object in it has unloaded. When a new object loads into this slot, Mario will hold a reference to this new object. The name "cloning" comes from one of its main applications, which is to duplicate objects such as coins or goombas. This name is a misnomer, as the duplication behavior is a property of those specific objects, and not the technique itself.
When Mario picks up an object by punching (as opposed to diving or water grab), there is a two frame window of time in which the object is not held, yet Mario has committed to picking up the object. At the end of this window, Mario will hold the object slot that this object is in, even if the original object has since despawned.
For example, if Mario begins to pick up a bob-omb just before it explodes and despawns, Mario will hold the object slot that the bob-omb originally occupied.
This can be performed using the following objects:
Loading zones cause all objects to despawn, and new objects to spawn in their place. If Mario is holding an object while passing through a loading zone, he will continue to hold the object slot, even though the object has unloaded.
Properties of clones
The term "clone" generally refers to an object that was not meant to be held that nevertheless is or was being held in Mario's hand
When Mario releases a clone, it stops updating and becomes unable to send signals to other objects. Mario can still interact with it, since interaction is part of Mario's behavior, not the object's. For example, while Mario can still collect a coin after it has been cloned, the coin no longer spins.
Though Mario can still interact with objects, certain types of interactions will cause the object to become intangible, and thus he will no longer be able to interact with it in any way. These include:
- Collecting a coin
- Taking damage from an enemy
- Touching a water ring
- Getting knocked back by a bully
- Touching a warp object
- Getting grabbed by an object
Some notable interactions that do not cause the object to become intangible are:
The behavior of clones is identical to that of objects during time stop.
Some objects such as coins and goombas use spawners, whose purpose is to ensure that these objects are loaded when necessary. For example, when Mario moves far away from a line of coins, they despawn. When Mario again moves toward the coins, the coin line's spawner is responsible for respawning the coins in the line that have not yet been collected.
When Mario interacts with a coin, he collects it and sets a flag on the coin to inform it that it has been collected. When the coin next updates, it despawns itself and informs the coin spawner that it should not be respawned when Mario moves away and comes back. However, if this coin was cloned, then it does not update, and so cannot inform the spawner that it has been collected. Thus, if Mario collects a cloned coin, and then moves away and returns, the original coin will respawn, effectively duplicating the coin.
The following objects can be duplicated in this manner:
- Yellow coins (not red coins, as these do not have spawners)
- Blue coins by reaching a loading zone before the Blue Coin Switch runs out
Because the cloned objects do not despawn, they gradually fill up the available object slots and continue to be rendered on screen. This can cause lag, game corruption, and eventually a game freeze when the object slots run out.
When Mario rides on a koopa shell, the shell object stays spawned until he runs into a wall or presses Z, which causes the shell to break. At this point, Mario sets a flag on the shell, and when the shell next updates, it despawns itself. Because a cloned shell does not update, it does not despawn, allowing Mario to repeatedly ride and break a shell after cloning it.
Remote star collection
Stars that spawn during the course of gameplay can be cloned. For example, this can be done with red coin stars, 100 coin stars, and stars contained in item boxes.
Even if a star is spawned at the start of a level, it can still be cloned if that level contains a loading zone, such as Board Bowser's Sub and Collect the Caps in Dire, Dire Docks.