Ah, Twitter hashtags. Nothing gets the juices flowing, eh? These four popped into my head instantly. They have two things in common: They changed my life, and I still enjoy replaying them.
The Kickstarter for Thimbleweed Park had a tier where one could be absolved of the sin of pirating Maniac Mansion. I did not need that one. I remember examining the box in my parent's living room. I remember mistaking "musician" for "magician". I remember having nightmares about dying from radioactive steam. I remember playing the hell out of Maniac Mansion.
Final Fantasy Legend 2
Dragon Warrior may have been my first RPG, but this is the one that made me a fan. The first game I replayed to see if the end-game dialogue was slightly different if I played a certain way. And it was. It was just one line of text but my mind was blown. And then I played it again. And again.
I didn't have my own copy of this until the Playstation port, and ended up hunting down a cartridge after my first year in college. I still cannot believe my friend let me borrow this after he brought it to my house to show me how awesome it was. I play this game every year.
Final Fantasy 5
This is why I am where I am today. Discovering that there were three "missing" Final Fantasy games blew my mind. The screenshots of FF5 were just astounding. So I started to learn Japanese. And here I am. I run a charity event based on this game. I have pages of notes of my own game design inspired by this game.