Morrowind was bundled with a video card I got, and thought I'd at least try it. I had no idea what it was or how it worked, and I fell headfirst into it. WEEKS thrown at it, and I never got bored.

After that, Oblivion was a letdown for me and I didn't get very far into it. Skyrim was great fun, but the lore was clearly secondary. (I eventually went back to Oblivion and found it a better story than Skyrim, but Morrowind is still the best.)