Are you looking for a Flash physics engine?
Well, now you only have to choose the one you prefer.
Let’s see how many engines we have (listed in alphabetical order):
Free AS3 open source 2D physics engine for use in Flash and Flex, released under the MIT License.
Its last update (0.45 alpha) is dated June 2007. Anyway, it’s the one with the most active community at Google Groups.
Open source port of Erin Catto’s powerful c++ physics library Box2D, it’s the most updated engine at the moment with its latest 2.0.0 version.
The Flash engine does not have a good documentation but you can start studying original Box2D manual
I wrote a tutorial on this engine here
Fisix Engine: www.fisixengine.com/
Currently at 0.5 (alpha) version, provides an interesting documentation and some of the most complete demos.
It’s not freeware, though.
According to the author, it’s in fact not a physics engine but an interface for simulating physics.
Its version is Alpha 0.1
In the zipped source you will find the API documentation and the source code is very well commented.
It seems interesting, too bad the demos are poor
It’s interesting to know the author wrote this engine to make the remake of an old game called Exile
Another porting of Erin Catto’s Box2D
The author is currently working on motor2, just after a couple of months he released the first version, so the projects seems well supported
More an experiment than an engine, from its source you can learn how to make your own physics engine
Which one will you use?