Valve Anti-Cheat (often abbreviated as VAC) is an anti-cheat mechanism developed by Valve Corporation as a component of the Steam digital game distribution platform. It is intended to defer, abate, and quell cheaters and such bad-faith players. VAC bans will appear on a banned player's Steam profile, as a "VAC ban on record".
VAC bans cannot be appealed to game developers or Steam Support. The system is entirely automated, and any VAC bans that are issued incorrectly will also be removed automatically.
Unturned (version 3) utilizes Valve Anti-Cheat as one of its anti-cheat mechanisms. VAC is only active when playing on VAC-secured servers. Servers can be manually configured to disable Valve Anti-Cheat, although this is not the default configuration. The server list provides filters for finding servers that have either enabled or disabled VAC.