6. Gamma World 3rd edition, 1987
Gamma World was the point where all of the gaming moments #1-#5 started to really come together. It was more than just roleplaying too because we really got into the creation of settings, rolling up NPCs, making monsters, equipment, cartographizing (yes, I just made that up) whole lands, and lots more.
Before Gamma World, roleplaying for me had some tentative steps and of course solid beginnings but Gamma World was the first time I personally put it all together. We had a lot of memorable post-apoc games starting with the box set you see here. It would expand of course, but it's important to note our games weren't always serious stuff, we were just having fun with it and seeing where the rules, and our imaginations, were going to go. This was the first time my gaming took a light-hearted approach, and for that I had such a good time, obviously a trend I would take with me, well, pretty much always.