My introduction to gaming was, I think, Atari's Combat.
What sealed the deal for my gaming addiction was the original "King's Quest" on my uncle's computer shortly thereafter. The graphics were only slightly less-crappy than the Atari's, but it had a story! My five year old mind had little difficulty with "get carrot", "open door", "look down" etc., so I played the heck out of it for the longest time. I didn't beat it until years later, when it was released on the Roberta Williams Anthology.
Ah, dusty old memories.