Lightspark is an open source Flash player implementation for playing
files in SWF format. Lightspark can run as a web browser plugin or as
a standalone application.

Lightspark supports SWF files written on the newest version of the
ActionScript language, ActionScript 3.0, which was introduced at the
same time as Flash player 9.

Optional Dependency

gnash can optionally be used as fallback support.