Over on rpg.net there is a discussion about games that fundamentally changed your views on RPGs. While I gave a few of my standard answers and the good happy things that changed my views at the end I had include something that didn't. Although not because of the game itself but because of people.
All the various editions of DnD changed my views but not in a good way. While I don't mind the actual games themselves, but it was the various edition wars and all around overwhelming amount of hate I saw getting tossed around. It changed the way I viewed the RPG community that the hobby had fostered. Making me see just how divided, petty and arrogant some people can be (even myself to some extent).
While lately I've been edition warring among a few other games myself it's usually been because of the cost of the new edition or how another is a cash grab, etc.
But Dungeons and Dragons players, especially online, take it to a whole different level of stupid. The amount of seething hate I've noticed just in discussions over various versions of the OD&D rules. People verbally attacking (and threatening physical violence) because someone likes fourth edition DnD. Others say you're an idiot for liking 3.0 over 3.5 over Pathfinder.
Seriously what the fuck?
I've never gotten to the point of violent threats over what I do or do not like. At my worst I may say that I will not be buying a new version of something with some colorful language. But I have been threatened for supporting what I like or refusing to support what I don't. My usual answer is basically telling the to come on down to Missouri where I live, I'm not that hard to find. Nobody has ever taken me up on that though.
For the record my personal likes in DnD versions would have to be as follows: BECMI version first, D20 Modern second and 3.0 as a third.