Mega Man X plays similarly to its predecessor series Mega Man, but with various new features: X has the ability to dash along the ground at any time, cling to walls and Wall Jump, and dash and jump at the same time, increasing his speed in the air. This all gives X more mobility than his Classic counterpart; these modifications make it easier to go through the majority of the game without using any other gun than the default, which is different from previous Mega Man games where players were more inclined to rely on weapons won in previous fights (Like Metal Man's infamous Metal Blades) against boss characters in previously conquered stages. X is also able to locate capsules that permanently upgrade a part of his armor, such as his helmet, boots, chestplate, or arm cannon. An upgrade common to each game is the ability for X to charge weapons earned from bosses, which gives them an enhanced secondary fire mode. In later games, there are multiple armor types available that can either be mixed and matched, or completed for additional armor set bonuses. In X3, Zero (the leader of the Maverick Hunters in the first Mega Man X) is a playable character from the beginning. In the second game, Zero is armed with a beam saber in addition to the traditional "buster" gun, but relies on his saber almost exclusively starting in X4. In X5, both X and Zero gained the ability to duck; an ability previously unavailable. In X6, there is a new rescue system where the player must rescue reploids. In X7, a new character known as Axl is introduced, playable alongside X and Zero. Axl utilizes two guns known as Axl Bullets. In X8, a new Double Attack feature is introduced, where two characters can attack at the same time. X8 is the latest entry in the franchise. Mavericks replace the Robot Masters, and Sigma replaces Dr. Wily. The Mavericks are based on various types of organisms (usually animals) instead of being humanoid in appearance, as were most of the bosses in the classic series, although their attacks and names are usually based on mechanical or chemical phenomena or laws of physics like the original games. Though some Mavericks have new, never-before-seen powers (e.g., Toxic Seahorse from X3), most have the traditional element-based weapons of the past games, such as fire, water, ice, lightning, wind, and earth.