Crisis Core begins seven years before the start of Final Fantasy VII, and encompasses the events that take place until just before its beginning. The game's hero is Zack Fair. He is a SOLDIER working for the Shinra Electric Power Company under Director Lazard Deusericus. The game tells the tale of Zack's battle against the villainous SOLDIER defector, Genesis Rhapsodos, and the other products of the Jenova Project. - Wikia
If you've played the game Final Fantasy VII, then without a doubt, you know Cloud Strife. In FFVII, Cloud is a proud swordsman who believes that he is part of SOLDIER, an elite group of Shinra warriors. As the game progresses, he begins to uncover some of the lost memories, and the reasons as to why are explained in the Crisis Core Playstation Portable (PSP) game.
Crisis core is the story of Zack Fair. His dream to become SOLDIER first class and his quest to be a hero. He met Cloud Strife, a Shinra infantryman, on a mission. Zack becomes Cloud's mentor and friend, They developed a deep friendship, unaware that it'll soon changed their destinies. It is also the story of the iconic Buster Sword.. On how this massive weapon came to be in Cloud's possession.
Zack Fair is not part of the original FFVII game (screentime only in flashback sequences) because by the end of Crisis Core, he died. I honestly didn't want him to die. I remember hoping and wishing that Zack would be able to kill all the the Shinra troops that attacked him. I remember blaming Cloud, because as an infantryman, he should have brought something as precious as phoenix down. (A phoenix down is a common FF item that enables a player to come back to life).
But such is Zack's destiny. And Cloud's, as well. With the Nibelheim incident trauma, his Mako poisoning and then witnessing his friend's death, Cloud's confused and tortured mind cracked.. and this caused him to merge Zack's persona and memories with his own. The game ends with him, entering Midgar with a new personality and as a SOLDIER 1st class, signalling the beginning of Final Fantasy VII.
Embrace your dreams. If you want to be a hero.. you need to have dreams. - Zack Fair
* The video is Crisis Core's full ending, English dubbed. I cried, the very first time I finished playing the game. I still shed a tear whenever I play and finish it again. If you've played the Crisis Core, I'm sure you'd agree with me that this is one of the saddest endings in the action Role-Playing Game world.