There are already many well-developed flash game engines. I will sort them all out. I hope it will help you develop games and learn the ideas. Both flash and Silverlight share the same idea.
These are only projects that I personally develop very useful for games. Some of them are only for games, some are useful components, and some also provide support for multiplayer games.
2d Engines
Flixel
A fully functional 2D dot matrix game development engine.GitHub
Maybe you once played a game developed using this engine.Canabalt
Flashpunk
Another 2D lattice game development engine.
Pushbutton
A 2D engine that integrates the box2d physical engine and supports multiplayer games. If you can access Facebook, try it.Youtopia.
ISO Engine
As3 ISO lib
As3isolib is a simple, high-speed and high-University engine that allows developers to focus on practical applications without learning complex APIs.
Theoworlds
"Theosdk was originally our own Distance Computing engine. It allows you to create your own map-based game ."
Isometric game engines
Openspace
Physical Engine
Flave-2D physical Engine
Jiglib-3D physical Engine
Box2d-2D physical Engine
APE (ActionScript physics engine)-2D physical Engine
Wow Engine-3D physical Engine
Particle Engine-Example Engine
3D Engine
Alternativa3d,Away3d,Papervision3d,Five3d,Sandy 3D
Tankionline
Some useful Class Libraries
As3 data structures for game developers (as3ds)-Many game development architectures.
Baseui
Layout structure similar to flex for flash
Vancura-AS3-libs
PureCodeImplements the skin and style of components and provides scale9bitmap support.
Browsercanvas
Dynamically adjust the flash size
Http://www.cnblogs.com/nasa