FlashDevelop is a free and open source code editor for every developer
FlashDevelop offers first class support for ActionScript (2 & 3) and Haxedevelopment. Great completion & code generation, projects compilation & debugging, plenty of project templates, SWF/SWC exploration etc. FlashDevelop
is also a great web development IDE with source-control support (svn, git, mercurial), tasks, snippets, XML/HTML completion and zen-coding for HTML.
Uses two-dimensional "sprites", 2D images created and used on a flat plane, as opposed to the three-dimensional models or environments found in 3D games.