Final Fantasy II is the original Japanese sequel to Final Fantasy. It is not to be confused with Final Fantasy IV for the SNES, which was renamed "Final Fantasy II" in North America.
The game introduces chocobos and an activity-based progression system, in which the characters' statistics increase depending on how they are used or acquired.
This movie by pirohiko demonstrates multiple major glitches that allow the game to be completed in an impressively short time. For more details, we recommend reading the author's comments.