Here, I'll start. When I was 8 years old, my parents went to a dinner party and plonked me down in front of the host's computer so I'd stay out of their way. The game they booted up to keep me occupied was Space Quest II. Little did they know what impact that would have on me...
It's funny to read comments bashing King's Quest 3, because freak show over here (me) got into adventure games because of KQ3.
Before my psychotic parents got rid of it for being occultic, and replaced it with Space Quest 1 (not a bad exchange, I must say) I loved KQ3. I never got far in it, but it was just this open world for me to explore. The fact that wizard guy could just poof in at any time just captivated my imagination and made it feel like someone other than my character was out in the world doing things. It made the world feel much bigger than it was and it captivated my sense of wonder.