Definitely the Halo of its Genre. KOTOR is a prime example that new game can still become classics. Thank you Star Wars!
Let's start from the beginning. the story takes place a long time ago, like before any characters from the movies even existed, in the time of a very old republic (hence the name). It begins with you, yes you, or whoever you want you to be, but for the sake of confusion, let's just call him guy. Guy is abruptly awoken on a ship being shot apart by a Sith destroyer (Yes, the Sith take a HUGE role in KOTOR) and is inevitably shot down on the sprawling city of Taris with the ship's captain, Carth Onasi. after you crash on Taris, Carth advises Guy to go out and find the Jedi, Bastilla, who was on the ship with them. I won't reveal the rest of the story, but you eventually meet up with a whole array of different party members ranging from jedi, to droids.
On the positive side, you are given absolute control over what kind of character you want to be. you are well capable of becoming a Jedi, but not until later. despite that armor and accessories are somewhat limited on the fact that the more you play, the more outdated your stuff gets. the game is very flexible by matter of choice, meaning if you enjoy being good to others, the light side is available, while if you prefer getting cash, killing innocents or just enjoy taking candy from babies, you are welcome to do so as well. Each side of the force is available and has its own benefits if you are completely loyal to whatever side you choose, you can even choose to be a gray force user, which is basically neutral. Another great thing about KOTOR is the characters themselves. each character that joins along side you in the fight for good or evil has their own back story and outlandish personality. for one, is probably one of the greatest characters ever made in a game (or movie). that character, is HK-47, the assassin droid who has his own twisted view on life that is so ridiculous, it's hilarious.
on the negative side, the combat system has a lot left to be desired. its too quick for those who need time to make a decision (unless you pause the game) and its way too slow for those more concerned with action packed lightsaber battles.