Headcode is an embedded scripting language that was originally designed for creating code that can be modified independently of the main program's source code and which doesn't require compilation. This can speed up the development process by eliminating long build times when testing small changes, and can also make a program extensible by the user without the need for full source code access. The system is designed such that scripts can easily be converted to bytecode at load time without significantly impacting the loading process, allowing for faster iteration overall and simplifying the process of making alterations for the end-user.

The system was built with performance in mind, so although the bytecode form of any script is interpreted at runtime, the overhead of such a process has been minimized. In HCGE, its use as the sole method of creating games with the engine not only provides the user with a simple interface to the engine's powerful features through an alternative to traditional programming languages, but it also means that any game created on any other platform will immediately be capable of running on any other platform which HCGE supports without recompilation or additional technical work. Headcode is also a part of the Methyl Engine as a supplement to the more-traditional use of native code, and can factor into development as much or as little as desired for each project. In the case of Methyl, as in the case of any program where the user can extend the program using native code, Headcode can also be extended by the creation of custom commands, even without exposing the system's core code.

Short fictitious example script