Have you tried the secret puzzle mini-game?

[Lone Wolf Leonhart]

The 15 Puzzle is a secret minigame in the original Final Fantasy that can be played after having obtained the ship, press X & O (or A & B) together a certain amount of times while on the ship to make the game appear. The goal is to line up 1 to 15.

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[VeloZer0]

Wow, I had completely forgotten about this, it's been a long time.

[Rez09]

Yeah, I love sliding puzzles and thought it was quite spiffy when I learned about it in the NES version.

[Wolf Kanno]

It was amusing, though I like the matching game in FFII a little better. Sad that they never kept these little gems in the rest of the series. I think only I, II, and IX had secret games like this.