flixel

Flixel is a free, lightweight, and open-source game development framework for the Adobe Flash Player, written in ActionScript 3. It was created by Adam "Atomic" Saltzman and released in 2009. Flixel is designed to make it easier for developers to create 2D games, particularly those with a retro or pixel-art aesthetic, by providing a set of reusable components and a clear structure.

The framework offers features such as a tilemap editor, sprite management, collision detection, particle systems, and audio playback. Its object-oriented design allows for rapid prototyping and development. Flixel's popularity stems from its ease of use, extensive documentation, and a supportive community that contributes tutorials and extensions. While Flash Player is no longer supported by major browsers, Flixel projects can still be compiled and run using tools like Adobe Animate or various open-source SWF compilers and exported to other platforms like HTML5 using technologies like HaxeFlixel. Many independent games and game jam entries have been created using Flixel.