The definitive classic role-playing/strategy game in the Final Fantasy universe.
No. Perhaps I should start with the graphics... so simple, sometimes abstract to an art - sometimes, as in the highest level magic and summons, breathtakingly brilliant.
No, that's not it either. Perhaps I should go into the sound and how each anthem rouses you to battle to your finest, in fields and swamps and castles and towns...
No, the gameplay... that's the key, right? Hundreds of abilities to be learned in the many jobs that you can carefully sculpt your fighting force into. The way that you can customize your team down to the smallest detail, even if you want to lead an army of Chemists carrying guns, is amazing. The game doesn't mind. It won't tell you you're crazy or wrong. And that's not to mention the bonus special classes of the special story characters that join you along the way, with their unique and sometimes over-the-top abilities. It's enough to keep you engrossed for hours, even enough to make me want to start over and try it all over a different way when I've finished!
No, that's still not it. Perhaps the best part of the game isn't in anything you can do, but in the things you can't. FFT has such a fully-realized universe that you'll find yourself wishing you could get your enemies and NPCs to permanently join your team with their unique abilities, skillsets, and equipment combinations.
There are characters like the Assassins Celia and Lede, Olan and his incomparable "Galaxy Stop", Delita showing off high-level Holy Knight skills before you get them for yourself, Magic Fencers, etc.... all different cool things you can never 'have'. They're just there to show that there is a universe and there are characters and skills and things beyond which you can experience first-hand. Square gives us a taste of it, just enough to know that the world is bigger than you, and lets us use just enough of it to feel important and satisfied and stops just short of giving it all in a masterstroke of genius. We always want more. We know there is more.
There's a reason that Final Fantasy VII started so many rumors, the alleged "Shadow WEAPON" and uber-materias and Aeris resurrection theories... it was believable. There were so many cool and secret things that you never knew how far the rabbit hole really went. FFT did the same in a totally different way and still succeeded wildly. It created a fully-realized world that sparked your imagination long after you finished the game and turned off the power. It made you think, if only for a minute, "what if...?"