GTweak is a command-line script that can be used for tweaking operating systems of Windows family. It has two modes of work: Wizard Mode (for average-skill users) and normal, prompt mode (also called advanced mode). First mentioned mode is the default, user chooses tweaks using keypad. Second is like command prompt, but program does not recognize standard commands. In order to see commands of GTweak, type ? (it shows ReadMe). GTweak has a simple scripting support (no piping or streaming, just linear parsing), which is described in gtweak.txt file inside the distribution package. Program does not use external utilities, excluding these appended to system. Almost all tweaks are reversible.