Lightspark is an open-source Flash player implementation written in C++. It operates as both a standalone desktop application (using SDL2 and OpenGL/Cairo for rendering) and a browser plugin via PPAPI and NPAPI. The codebase implements ActionScript 3 (AVM2) and ActionScript 1/2 (AVM1) runtimes, supporting a broad range of Flash APIs including display, audio, video, networking, text, and filters. It includes a custom test runner framework with recorded input event playback for deterministic regression testing. The project is structurally well-organized with platform abstraction layers (paths, directory iteration, event loops, threading), but many Flash API classes remain stubs (emitting 'not implemented' warnings). Third-party dependencies are heavily vendored (pugixml, nanovg, imgui, cpptrace, cereal, etc.), some of which are outdated. Given the deprecated nature of Flash technology, the codebase exhibits significant technical drift despite occasional updates.