Of course, I had played role playing games before then, like first edition Dungeons and Dragons. However, those three games were the first really serious campaigns I was in and really made role playing games a serious hobby for me. Of course, the groups I played with get the real credit but the systems still help.
Dungeons and Dragons is the bedrock of role playing games. It's the game that got the industry started and I don't think role playing games would have inevitably, spontaneously come to life. They needed a spark and it turns out that a dragon is a pretty good spark.
I do know some gamers who actively dislike D&D. I think it's because D&D is the Man of role playing games and it's hip to hate the Man. And, as litigious as TSR would be, sometimes they really did act like the Man.
However, decades of development and changes and ideas has given Dungeons and Dragons one of the richest and most genuinely diverse contents out there. It has so much to offer. For a game that isn't designed to be a generic system that you can apply any theme to, it has a wealth of sandboxes to play in.
If I could only play one game for the rest of my life, it would be a tussle between Dungeons and Dragons and Go. Mind you, I'd argue I could play every edition and make a monk who plays Go and insist on playing Go, just in character.
I have to admit that reading the second edition of Call of Cthulhu's rules in middle school was my introduction to H. P. Lovecraft and I have been reading his works and the works he inspired. It's been a lifelong enjoyment and not a year goes by without me rereading some of his stories.
If you somehow don't know what Call of Cthulhu is about, it is a horror game inspired by the guy who helped define cosmic horror. You play relatively ordinary people trying to make it to the end without dying horribly or going insane.
Call of Cthulhu, particularly when it first came out, was really the role player.s role playing game. An investigator with a Bowie knife, a tommy guns and some dynamite will probably take out some deep ones. But against anything real monsters, let alone Great Old Ones, you will just die horribly. So you have to focus on playing the character, not fighting.
Back in the day, I was a little sheepish about playing Marvel Super Heroes, since it was such a simple system where one chart did most of the work. But I have had years of fun with it and even occasionally play it now.
And with such a simple system, it was easy to hack the system and play with the mechanics. (My primary GM didn't use the Marvel setting, just the rules, so we populated it with all of our own heroes and villains) I didn't really do that seriously until the third edition of Dungeons and Dragons but Marvel Super Heroes gave me a good start.
And, frankly, it was all such comic book silly fun :)
I've played and researched a lot of indie games in the last few years. But I really owe my grounding in the hobby and my love of the hobby to these old school games.