My heart wants to say Ocarina of Time. I rented it from Blockbuster 3 times before my parents caved in and purchased it. I couldn't believe that games could be like that. I was blown away by a wide open world with multiple towns, genuinely challenging puzzles, many secrets, time travel and a story I cared about. However, my brain wants to say Command and Conquer, I probably wouldn't be a software engineer if it wasn't for C&C. It was the first game I modded. It got me into PC's and figuring out how to make things on PCs bend to my will. Now, when I watch Mr Robot, I'm like, 'oh I know how to do that'.