The Simpsons: Bartman vs Radioactive Man is the first game I ever owned, but I had never finished it. I resolved to give it a proper good try this week while I'm down at home.
So I sat myself down to finally play. After fumbling around with my Toploader NES and a dodgy RF cable, I ended up resorting to the front loader.
And I finally finished it. It was the first game I ever owned, and here I am 20 years later having actually finally finished it. The feeling of accomplishment is just... just so great.