The first adventure game I bought and played was an Infocom interactive fiction ... I think it was Stationfall. Before I had briefly played Magnetic Scrolls' Fish! at someone else's computer. Fell in love with text adventures and started collecting them, I have a few of the Infocom folios as well (sadly not the Starcross saucer). The first graphic adventure I remember playing was King's Quest IV.
These games, along with later games like Monkey Island, had a huge influence on me, I learned programming to write adventure games myself but spent more time writing adventure game engines (both text and graphic ones) than actual games, and today I'm a software engineer (not in the game business).