Silencer was a game from Mind Control Software, playable online through the WON (World Opponent Network) service, which was discontinued by Valve in favor of the Steam platform. Along with the demise of WON.net, Silencer went with it. zSILENCER is a re-creation of the original Silencer game.

Silencer is multiplayer only, and is essentially a team based capture-the-flag style game. You navigate your player to active computer terminals strewn throughout the map and siphon files off of them, until a Top Secret file is acquired. You pick up the secret file and bring it back to your base, careful of opposing teams trying to kill you and steal it for themselves. When your team returns three of these files, you win.

Each team must spawn their base "door" somewhere in the level, usually in a strategic spot. Teammates enter and can heal their shields and health, buy inventory items, and the back of the base is where the secret file must be returned.

There are five "agencies", each with special stats or unique items, and online supports up to 24 players in a match at once. Play a 1v1, 2v2, 3v3, or 3v2v4v1, anything is possible.