Misbehave in a Steam game and its developer now has the ability to detect you and get you permanently banned.
Valve has opened up the possibility for developers to implement their own systems for identifying disruptive players, in addition to its own anti-cheat software.
Developers who are alerted to a player's misdeeds will then be able to instruct Valve to apply a permanent ban as punishment.
Steam explained the decision in the following announcement:
Banned by Game Developer (Game Ban)
Because nobody likes playing with cheaters.
Playing games should be fun. In order to ensure the best possible online multiplayer experience, Valve allows developers to implement their own systems that detect and permanently ban any disruptive players, such as those using cheats.
Game developers inform Valve when a disruptive player has been detected in their game, and Valve applies the game ban to the account. The game developer is solely responsible for the decision to apply a game ban. Valve only enforces the game ban as instructed by the game developer.
For more information on a game ban - and presumably to appeal - players will now have to contact the developer of the game itself, rather than Steam.
Valve boss Gabe Newell recently complained about the amount of extra work the company's support team had needed to put in to firefight the controversial introduction of paid-for mods. The company U-turned on the initiative shortly after.