What's the most meaningful game(s) you've ever played?

[naznatips]

choirsoftheeye said:

This question will make my answer significantly more RPG-centric than a "What games are your favorites, etc." type question. (not in order)

I know

I didn't want it to be what's your favorite game.  A game can be really meaningful to you without being your favorite, and of course RPGs will be the most common answers because they are more character and plot driven than most games.