The gameplay in Mega Man X4 is similar to the previous installments of the Mega Man X series. The player is presented with a series of action-platforming stages that can be cleared in any order desired.[1] In these stages, the player must avoid obstacles like falling debris and spikes, and destroy enemy robots to reach the end of the stages. Some levels contain ridable vehicles such as hover bikes called Ride Chasers and mechs called Ride Armors.[2][1] The player character's maximum health can be extended by obtaining a "Heart Tank" in each of the eight stages. Two "Sub Tanks" can also be found, which can be filled with life energy and then be used to replenish the player's health at any time.[1]
New to Mega Man X4 is the ability to play through the game either as X or Zero fully, (while Zero was playable in Mega Man X3, he acted only as a backup for X). The two characters cannot be switched during a playthrough. Though both of them go through the same stages, they operate differently and are challenged differently from the terrain.[3] X wields the "X-Buster", a plasma cannon on his arm that he uses to attack foes from a distance. It can be charged to fire stronger shots.[1] A new weapon is given to the player with each boss defeated while playing as X. These weapons have limited ammunition. In some stages, the player can find hidden capsules that contain armor upgrades that greatly enhance X's capabilities.[1] Zero is more melee-oriented than X by using a "Z-Saber" sword. Rather than acquiring weapons from the bosses (with the exception of his Giga Attack), Zero learns special techniques that do not require ammo such as the "Hienkyaku" air-dash and "Kuuenbu" double-jump.[1] However, Zero cannot upgrade any of his body parts in this game.[3]