I was introduced to Popfly nearly a year ago now, and recently I have been having a bit of a play and developing my own game with it.
The main feature of Popfly is the ability to quickly and easily create games, mashups and parts of mashups using a very simple drag-and-drop user interface. It’s really easy to get started with projects, and if you need to do something complex for some reason you can simply click one button and drop back into the code behind it and make the change you need!