Like R0J0 the first game creator I started using was Klick n' Play.
My brother had a game magazine from around 1996 that had a small ad about it, but I only discovered it in 2002 when I found the magazine in a box and decided to revisit it for some nostalgic feelings. I then found some websites and communities about game creation and started using it.
Not so long after I discovered its successor The Games Factory, then Click n' Create, and some time after Multimedia Fusion. I used a lot the MMF 1.5, never finished a game but did some small useful applications.
Those were good times. I remember being lurking around the Clickteam's forums. At that time Ashley (AKA Tigerworks) was one of the best independent plugin makers for MMF. I was not very active at that community but I made some small contributions. I think I was one of the first to introduce the idea of multiple action points by then. Unfortunately they never made it into MMF2, but luckily Construct did!
So after trying briefly MMF2 I discovered Construct. At first I was not very attracted by it since it looked almost the same as MMF2 and yet very buggy. Influenced by Blender success, what later brought me here was it's open-sourceness. And with it the idea that I could use my years of experience with similar softwares, added to my design knowledge, to collaborate in a community effort to make the perfect game maker.
I was already working in a new interface proposal for the yet to come new Construct, when they suddenly announced C2. Unfortunately, soon after Scirra decided to go commercial and closed-source. Still, I liked the community and the improvements Construct had over Clickteam's system. Since then Scirra proved to know how to have a very nice company-user relationship, without being too greedy like most companies do, so I sticked with it.