Knights of the Old Republic (
KOTOR I) is a single-player RPG released in 2003. Despite its age, it remains very popular. Among other things, there's an active
subreddit related to the game. You might even see me in there.
A remake is planned, but not much is known about it yet. In the meantime, you can assume that everything herein applies to the original.
The general feel of the game is (in my opinion) similar to A New Hope or The Force Awakens - an epic Star Wars romp that includes some great plot points and doesn't take itself too seriously (in a good way). There is one huge plot element that if you know it beforehand - well, it doesn't ruin the game, but it is a lot better to experience for the first time actually in-game than just reading about it. So if you don't know the plot of the game yet and you're thinking of playing it, don't read too much about it. Feel free to check out my non-spoiler tips, or the similar set of non-spoiler tips on the
subreddit. That'll be enough to get you through a successful playthrough without ruining anything.
One weak spot of the game is that a lot of the Dark Side dialog is pretty corny. So if you plan to play Dark Side, just know that you'll be more of a cartoon villian than a subtle schemer.