GameGuts is a collection of low-level services for game development. It is not a game engine; it is a foundation on which to build an engine. A DLL with a C API, targeted at higher-level languages. Includes bindings for .NET, more to come.
This project is an attempt to create a wrapper between filesystem code for one operating system and compile it for another. For example, a Linux filesystem driver could work natively in Windows if the project goes as planned.