Almost three years after launch, Civilization V's promised Pitboss multiplayer mode is finally arriving today in a new patch. The update also brings an observer mode, support for custom maps in multiplayer, AI tweaks, new terrain art, bug fixes, and more, making everything spick-and-span for the launch of the Brave New World expansion next week.

Pitboss is, in the words of the patch notes, a mode "which allows players to connect, take their turn, disconnect, and come back later. Email notifications and steam notifications are built into the system." A more laid-back mode for people who don't want to sit and play a round for several hours straight, see.

At first Pitboss will require someone to act as server, but developer Firaxis plans to release a standalone server that doesn't require a Steam account, "once the system has received a healthy amount of feedback from the community"--ie it's ironed out bugs and niggles.

The patch brings loads of other fine changes, especially to multiplayer, so do check the notes. It's due out later today, and should update automatically through Steam.