wonderfl is an excellent service which allows users to input ActionScript 3 code in the textarea to the left, then compiling the code on the server side and running it for immediate results inside the window on the right. The term 'fork' refers to modifying the original code (either by the author or other users), then saving it under your profile name so that anyone can view it or change it even further.

A Google account of Yahoo! ID can be used to register for the free service.

Kei Mesuda had recreated his excellent Nomltest FS shooter using wonderfl (under the new name Tiny Cannon ML), while the legendary Kenta Cho designed a couple of originals such as CircleCycle, Ascii Art Ship and BallBlast with the versatile application as well. There is even a simple shooter with red pixels which propagate around the screen based on Conway's Game of Life theory. If those don't interest you, then there are always classics such as Tetris and the cave flier game. (source: the2bears)

wonderfl: build flash online