Valve's item system for Team Fortress 2 has been a resounding success, but it's seen an unscrupulous few, idle in games simply to get their hands on new ones. No longer though, as Valve has updated the game, meaning you have to be actively playing in order to receive the rewards.
“As of last week, players can no longer receive item drops unless they are actively playing the game,” said the developers in a statement.
Of course though, it isn't as easy as just rewarding players that are consistently on the move. What about the campers of the world? They're actively playing but they don't look busy in some senses. With this in mind, Valve created a checklist of what constitutes an active player: they're connected to a VAC secured server, they respond in a timely manner to item drop notifications without using an external program, they're only running one instance of the game and they're not in text-mode.
Don't think you can't leave the client running and go grab a drink of something though, you won't be banned for sitting still for a few minutes, you'll just not be earning rewards during that time. However, you can now be banned from VAC servers if found to be using any software to help get around idle-detection.
KitGuru Says: The multiple instances thing was something I always thought was weird. People do that with MMOs – multiboxing they call it. Can you really claim to be playing a game (and enjoying it) if you're trying to run several versions at once? [Thanks PCGamesN]