KOTOR is what got me into BioWare games. I spent my childhood rewatching the original Star Wars trilogy continually then was loving the prequel movies (I didn't know any better) so anything Star Wars related, I was eating up. Then I saw at Toys R Us that a new Star Wars game called Knights of the Old Republic had just released, and I begged my mom to get it for me. First several hours, I was primarily trying to figure out how the hell gameplay worked but once I got it down and was able to start focusing on the characters and the story........god damn did it floor me!
Later that year I got the first 2 Baldur's Gate games and was completely hooked on BioWare after that.