"When I started working in the game industry, it was at Gen Con. My very first day working full-time (not as an intern) for ICE was at Gen Con 1990. It was also my first Gen Con ever. I had never had the opportunity to go just as an attendee, for fun.
For those first few Gen Cons, my job was to "work the booth" a few hours each day, which meant sell product and chat with gamers. It was fun, actually, and got me into the habit of talking to and even making friends with the people who play the games I worked on -- something slightly rarer than you might think.
Then I went to work for TSR, and Gen Con really changed. TSR owned the convention, and everyone was required to work eight hours each day on some aspect of the convention, either "in the castle" (the TSR booth looked like a huge castle at the time) or in some other way, like selling tickets, organizing events, and so on. It was a lot harder to have fun at Gen Con with so much responsibility. TSR also valued game demos very highly and ran five or six of them in the castle for its different game lines. This was pretty worthless, actually, because you can't "demo" a setting in 15 minutes, and while you can demonstrate a game in that amount of time, who at Gen Con in the 1990s needed a demonstration of how to play D&D? But we didn't make the rules, nor could we effectively comment on them. "