(Note: As the PlayStation 2 is backwards compatible with the original PlayStation, the original Gran Turismo and Gran Turismo 2 can also be played on the console.)

As for whether GT1 is worth playing, it's arguable depending on what you're looking for. GT2 does everything GT1 does but better and with more content. But if you're a fan of the GT games then GT1 is still worth playing even though 90% of what you're doing isn't unique.