Derevel is a build system. The idea is that a build system should be flexible, easy to use, and not require many components that must be installed. With Derevel, a build C file is compiled and linked against a library that provides a cross-platform API for the most-needed functions a build script must have. This compiled file can then be used easily to compile the program, and this Build Executable only needs to be recompiled whenever the build script changes.
Because most projects, especially on Linux, now require the user to do compilation, this will hopefully simplify the things that need to be installed or run by the user. Almost all of my projects, including Derevel itself, now uses this build system.