Priority

In fighting games, the priority of an attack refers to its ability to cleanly beat other attacks of the same type, resulting in the character using the higher priority attack interrupting the opponent's lower priority attack and successfully dealing damage to the opponent.

There are two types of attack priority: physical attack priority and projectile priority.

Physical attack priority
Just as a punching arm in real life can be hit, most physical attacks will have a collision hitbox within the attacking hitbox to identify that limb as an extension of the character's body that logically, should be able to be hit. If that collision hitbox is hit, the attack is interrupted.

Physical attack priority is determined by using that attack of the character in an attempt to trade hits with an opponent using an attack of a similar type, such as a standing punch against another standing punch. Attacks that tend to trade hits or be beaten by other attacks very often are considered to be low priority, while those that can cleanly beat other attacks very often are marked as high priority.

Infinite Priority


An Infinite Priority (IP) attack is an attack which possesses an attacking hitbox (CLSN1) but no collision hitbox (CLSN2) within that attacking hitbox.

As a result, when the attack is used to trade hits, the opponent's attacking hitbox will be unable to hit the character's collision hitbox, while the attacking hitbox of the first character will be capable of hitting the opponent's collision hitbox. Thus, the first character will always be able to hit the opponent out of his move.

Infinite Priority attacks are generally frowned upon by the M.U.G.E.N community, and some guides even dedicate sections to ensuring that attacks are not infinite priority through the proper deployment of collision hitboxes. However, they are still acceptable if it is for porting accuracy or if the animation clearly shows that hitting the location of the attack hitbox would not be expected to interrupt the attack (such as a sword swing).

Projectile Priority
If the hitbox of a projectile comes into contact with the hitbox of another projectile, they will interact. The priority of the projectile determines the outcome.

Every projectile has two priority-related traits, defined in the engine documentation as follows: projpriority Specifies the projectile priority. If the projectile collides with another projectile of equal priority, they will cancel. If it collides with another of lower priority, it will cancel the lower priority projectile, and the higher priority one will have its priority decreased by 1. Defaults to 1. projhits Specifies the number of hits that the projectile can impart on an opponent before it is removed. Defaults to 1.

These two values determine the behaviour of the projectile when it interacts with another projectile.

Note that projectiles with multiple hits of priority 1 will lose a hit on interacting with a higher priority projectile, but still continue to their target.