Silencer is a multiplayer-only video game released by Mind Control Software for online play using World Opponent Network technology. It combines elements of sidescroller games with other Sci-Fi action games such as Crusader: No Remorse. In the game, there are multiple competing agencies that send agents into the field to hack public computer terminals, with the goal of exposing the Martian government's secrets. Agents in the same agency could work as a team, and agents could buy a variety of items and weapons to help their team excel or to hinder an opponent.
In May 2001, the game was pulled from online play when Won.net went offline. Several efforts to re-establish the game have been made, with many veterans of the game community spearheading different projects (ranging from circumventing the authentication present in the original binaries to rebuilding the game on another engine as a mod or from scratch in Python).
On September 17, 2007, Arsia Mons, a veteran group who has reversed engineered the software, released an installer that allows easy playability. Currently, around 30 players are involved in playing on a privately-owned server that is open to the public.
In July 2009, O2, a Silencer clone that is still in development, released its first technical preview to the public. On December 5, 2010, another preview was released to the public; it is reported that the project is active.