If you recently used a cheat engine to unlock all weapons or attachments, but you don't have the achievements for those items, the game will tag you. Check your Steam achievements. If you are using a weapon that requires "The Secretary" achievement (Hitman 2 DLC) but you don't own the DLC or have the achievement, you will be tagged instantly.
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If you are a legitimate player who has been incorrectly tagged, through Steam is the best first step to fixing the issue. If you recently used a cheat engine to