Getting a multiplayer match going used to require some knowledge about IP addresses and ports, on both sides of the connection.

The multiplayer menu now offers three kinds of matches. A public match runs over the game tracker, which brings host and players together without anybody having to enter an address or a port. For a private match the players only need the host's address and a single port, and players from the host's local network and from the internet can be in the same match. A LAN match is what it says.

The host now loads the level before the lobby opens.

The network code has become faster and more compact: everything urgent goes out in one packet per frame, weapon states are only sent when they change, and positions take a lot less space than they used to.

Missions a player doesn't have are downloaded from the host automatically. If you have a mission of that name, your own copy is checked first and is never overwritten.