VAC and Game Ban enabled games can either be bought for your own account, or gifted immediately. They can no longer be saved to your inventory for trading purposes. If you directly gift a game to someone who gets permanently banned, you won’t be able to gift that game again.
Many games on Steam utilize the Valve Anti-Cheat System (VAC) or third party anti-cheat technology that can result in cheaters being banned from secure servers for multi-player games. You can learn more about VAC here. VAC bans are permanent.
Game Bans are used by game developers to address malicious behavior that falls outside of VAC detection. Game bans are determined by the game developer; they can range from single day bans to permanent bans. You can learn more about Game Bans here.
When a user is caught cheating, their Steam account is banned from playing multi-player on secured servers. This creates an incentive for people who cheat to stockpile copies of games on one account and to gift them to low value accounts where they can continue cheating. In response to this problem, Steam no longer allows users to purchase copies of VAC or Game Ban enabled games to their inventory. Additionally, if an account has directly gifted a game to other players who have been VAC or permanently Game Banned, then that account will lose the ability to gift that game.
We’ve taken these steps to ensure the integrity of the multi-player experience for those participating in online gaming communities. We understand that the restrictions on buying to inventory may be inconvenient for some legitimate users, but we believe that these steps will reduce the number of cheaters you’ll play against. And that’s important in having an online gaming experience that’s fair and enjoyable for everyone.