First Game Dungeon Mastered

Ah, that was a long time ago.  But for me it was the original Chivalry & Sorcery by Fantasy Games Unlimited.  In 1978, when I was a junior in high school, I met a fascinating fellow student who introduced me to RPGs by running a game of Chivalry & Sorcery for me. Naturally I played an elf fighter (duh!).  Then he transferred to another school and I was the only one with the books.  I whipped up a world map and threw together a story line.  It began with the party leaving the tavern at closing time, hearing a fight in a dark alley, and arriving just too late to save some dying guy who'd been attacked.  The dying guy asks them to return a small wooden box to a city in the elf land, then drops dead on cue.  From there I just added new stuff for each session based what happened this session and what the players had talked about doing in the next session.  I had about 4-6 core players and 1-3 who would sort of half play and half just hang out to enjoy the story and watch me do funny voices.  I think my talking eagle impression was the high point of the campaign.