From the website:
flixel is a completely free collection of Actionscript 3 files that helps organize, automate, and optimize Flash games; an object-oriented framework that lets anyone create original and complex games with thousands of objects on screen in just a few hours.
Use of Procedural Content Generation Methods
Flixel is designed for and has been used as the basis of a number of procedural games, notably Canabalt.
PCG Wiki References
Flixel - Wikipedia entry for Flixel.