The Force is -as says in the title- a "multipurpose 32-bit graphical user interface and window manager". That means that The Force is a program that provides a user interface made using graphical content, that can be used for many things (multipurpose), it's written in and for 32-bit processors and also it is a window manager (which manages overlapping windows). In other words it's a GUI.

    Currently The Force runs under DOS-compatible operating systems (such as MS-DOS, DR-DOS, FreeDOS, Windows 95/98/ME, Windows 2000 and later... (however with some issues with the video modes and the mouse, since Windows 2K and later are not 100% DOS compatible). An effort will be done (much later) to port The Force to other command-line based (and maybe not only) operating systems (such as Linux and FreeBSD).

    The Force relies on the Allegro library in order to communicate with the world (iow: to display graphics and take mouse and keyboard input).