In particular, Zero has befriended one of the leaders of Repliforce, Colonel, so much so that they have become fast friends, and Zero has shown affection for Colonel's sister Iris. One of the largest and strongest Reploid armies, known as the Repliforce, have developed strong ties with the Maverick Hunters, with their similar ways in honor and the desire for peace. The Maverick Hunters, ever growing, have begun to wipe out the remaining Maverick resistance, and have been heralded as the keepers of the peace. Since then, the Reploids are now living in peace with humans, and many large Reploid armies have formed, each one at peace with one another and growing every day. After Sigma's plan to use Doppler to spread the Maverick virus failed, Reploids X and Zero have begun to help build a world where no Mavericks exist. Many months have passed since Sigma's third defeat and the death of the renowned Reploid scientist Dr. This time, you'll be able to play as X or Zero for the entire game, giving the game two unique storylines to follow. As the first X game to appear on the Sony Playstation, Mega Man X4 introduces new 32-bit graphics, superb music and sound effects, as well as huge stages and an intriguing storyline.