Polymod is a Haxe library that enables modding for games and applications by intercepting asset loading and providing a runtime scripting system. It supports multiple game engines (OpenFL, Lime, HEAPS, NME, Flixel, and custom backends) through a clean abstraction layer of backends and file systems. The core API (Polymod.init, scan, loadMod) allows developers to define mod root directories, load mod metadata, and apply asset replacements, text merges (XML, JSON, CSV, TSV), and script modifications. A notable feature is the integrated HScript interpreter (a fork of the language) that allows mods to define classes, override methods, and extend game logic at runtime. The codebase is well-structured with clear separations of concerns (backends, file systems, format parsers, utilities) and includes extensive sample projects demonstrating integration with various frameworks. However, it lacks a formal test suite, contains some debugging artifacts (trace calls), and relies on heavy macro metaprogramming for scripted class generation, which increases maintenance risk across Haxe compiler versions. The dependency on Lime/OpenFL internals and platform-specific conditionals makes the code somewhat brittle, though the core abstractions remain reusable.