PSilent CS 1.6 is a custom version of Counter-Strike 1.6 that has been modified to include various new features, updates, and gameplay mechanics. The game is based on the original CS 1.6 code but has been extensively modified to provide a more enhanced and balanced gameplay experience. PSilent CS 1.6 is often referred to as a "custom" or "modified" version of the game, as it deviates from the original code and includes a range of new features and updates.