Dissidia 012 Final Fantasy (also known as Dissidia Duodecim) is the prequel/sequel to the original Dissidia: Final Fantasy. Like the original game, Duodecim is a crossover fighting game that pits major characters from throughout the primary Final Fantasy series against each other. It was released on the PSP in Japan March 3rd, 2011, March 22nd, 2011 in North America and March 25th, 2011 in Europe.
The gameplay remains mostly the same from the original Dissidia (details can be found here), with a few new mechanics and improvements. The original's destiny board and DP-based overworld has been overhauled in favor of a robust world map, gateways, and the introduction of a new currency KP, kupo points. Earned by completing certain victory conditions, which vary depending on the gateway, KP is used to acquire rare weapons, armor, accessories, and summons not available for purchase with gil in the main shop. In the story mode, some gateways will have level caps for KP - if the player enters with a character lower than the cap, bonus KP will be awarded based on the difference in levels. However, if the player enters with a character at the cap, no bonus KP is awarded and if the character enters with a higher level, the gateway is started with negative KP. For this reason, it is possible to adjust every character's level accordingly (up until their most current level, no higher). Experience gained while the level is adjusted will still be awarded, however, until the level is readjusted to the most current and highest level available, the character will remain at the adjusted level.
The combat system also received a few changes - in addition to the EX bar used for limit breaks, there is now an Assist bar to summon an assist character for attacks. The assist bar fills whenever an attack is performed, regardless of whether it connects or not. At the first level of the bar, summoning an assist will have that character perform a bravery attack. At the max level of the assist bar, the assisting character will perform an HP attack. Assist characters can also be attacked during this animation and if attacked, the assist bar will lock, preventing tag-ins for a brief period of time. The assist characters can also stop a combo if being attacked while activating, but this also causes the bar to lock temporarily.
Added to the EX bar functionality is "EX Revenge," performed while being attacked and activating EX Mode. Doing so will slow down your opponent dramatically for a period of time or if the player lands an HP attack.
It is also now possible to fight with parties. The battles are still one-on-one, but depending on the size of the enemy party, one battle can turn into a series of separate battles. If the first member of the party falls, it goes to the next party member and so on and so forth until the enemy party is defeated. All characters in the party gain the same amount of experience (assist characters do not gain experience, however) but if a character falls in battle, he/she is KOed for the duration of the gateway (in story mode) or for the rest of the battle (in aracade mode).
There are two full campaigns - one explaining the events of Duodecim, the war between Chaos and Cosmos before the events of the original game and containing the new characters and the other basically rehashing the original game with the original cast, except with the new gameplay mechanics in place. Additionally, there is also an arcade mode, a card-based battle mode, and "Reports," which fill in some missing gaps between the main story campaigns. Sometimes, the Reports involve battles.
The full roster includes all of the playable characters found in the Original Dissidia along with 9 new combatants. The new characters are,
Dissidia Duodecim Prologus
At a Square Enix event on January 18th, 2011, it was announced that a "paid preview" of Duodecim would be immediately available for the Japanese PlayStation Network for 300 yen. Included features are an exclusive scenario mode, that wont be included in the main game, arcade mode, and the ability to carry over your accessories to the full game and add Aeris/Aerith Gainsborough as an assist character in the final version of Duodecim.