Flash has always been a popular platform for web games. While we used it for some websites, there was only one game that I made on it, an advergame for Gilette that was a simple goal-kick simulator.

Gillette Champions Street Soccer

Nevertheless, when working on CasualCore, we used GameSwf for the UI played and integrated Flash swf files so artists could use all the features of Flash and Actionscript. Even today, a lot of my UI systems design is inspired by Flash.