Final Fantasy II Gameplay

Screen of condition in Final Fantasy II, where it is possible to see the level of training with every weapon.

Final Fantasy II is unique in the Final Fantasy series for not utilizing experience-based levels. Rather than earning experience points at the end of every battle, each character participating in battle develops depending on what that character does during battle. For instance, characters who use a particular type of weapon frequently will become more adept at wielding a weapon of that type, as well as increasing in physical strength.
Characters who frequently cast a particular magic spell will learn to cast more potent versions of that spell, as well as increasing their magical power rating. HP and MP, similarly, increase depending on need: a character who ends a battle with only a small amount of health remaining might earn an increase in maximum hit points, and a character who uses the majority of their magic points during a single battle might increase their maximum magic points.
A handful of bugs related to this advancement system remained in the released version of the game. The most notable of these bugs was the ability to cancel a previously issued command and still gain the statistic-increasing benefits of having performed it. The game's turn-based battle system gave the player the opportunity to input commands for all four members of the battle party at once. At any time before the command for the final character in the lineup was issued, the player could hit a button and return to the previous character to reissue a command.
Since many statistics, such as weapon and magic spell proficiency, were based on how many times a particular command was used in battle, a little patience meant it was possible to quickly advance in proficiencies in the space of a single battle round. A similar problem manifested in the way hit point increases were granted, which allowed characters to attack members of their own party to increase their maximum hit points. These problems were faithfully replicated in both the WonderSwan Color and the PlayStation ports of the game. The Game Boy Advance remake eliminated the command cancel bug, though the hit point increase trick remained. Various other changes were made to the Game Boy Advance version, including regular maximum hit point increases outside of those gained as outlined above, to decrease the difficulty of the game.

Battle parties consist of four characters at a time. Three of these characters are present throughout the entire game, but the fourth position rotated amongst a variety of characters throughout the course of the game. Final Fantasy II was the first game in the series to allow a friendly character to be placed in the "back row" during battles. Characters placed in the back row were immune to most physical attacks, but could be harmed with bows and magical attacks. In a similar vein, enemies could be arranged in up to four rows of two creatures each (for a maximum of eight hostile creatures on screen at one time). Only the two rows closest to the player's party could be damaged with physical attacks: by eliminating the two closest rows the player could then physically damage back rows of enemies.
Throughout the course of the game, when in conversation with non-player characters (NPCs), the player has the ability to "learn" special words or phrases, which can later be repeated to other NPCs to gain more information or unlock new actions. Similarly, there exist a handful of special items that can be shown to NPCs during conversation, which have the same effect.