The game doesn't come with a serial number by default (you'll need to contact support to get it), so I don't see a point for it.

I see. You're right.

Welp, just noticed that Victor Vran's serial number is actually used for multiplayer, so I added the game to the list as well.

Just like the base game and the Ashes of Urh'Rok DLC, the Embers of Rage DLC also comes with its own serial, as confirmed by Judas.

Moved Cossacks Anthology to the obsolete section, as the official servers have shut down and LAN play doesn't require a serial.

Just like the base game and the Reign of Giants DLC, the Shipwrecked DLC also comes with its own serial, as confirmed by Judas.
And since Don't Starve has a bundle pack now, I added it to the mix, as well.

Added Frozen Cortex.

Two Worlds is now the first pre-2012 game on GOG to gain automatic serial generation. You no longer need to contact support to gain one! \o/

Updated the list and mix to reflect that change.

Kind of sucks because Far Cry multiplayer blows with less than 8 people, and getting a LAN party of 8 or more people together in 2016 is next to impossible, so it more or less might as well not even have multiplayer now. :)

Don't you just need to setup a VPN and have everyone connect to it? Latency may of course become a problem if the game expects it to be near-zero, but if it originally played fine over the internet then maybe it will be fine with some.

Never tried myself.

Added Crashlands to the list/mix.

Trying to find 8+ people that you already know or that you might want to play Far Cry multiplayer with, who also are capable, willing and able to install and set up one of the popular VPNs used with gaming, and walk them through optimizing the configuration to work as best as possible through their firewalls is a huge pain in the ass to do with 1 or 2 people let alone organize a session with 8+. All that without even knowing if the game would work well through it to begin with. Additionally, Hamachi only allows 5 people within a VPN mesh unless you pay for it, not sure about Tunngle or other software, but to even try this most likely every single one of the people would have to shell out money to buy a VPN solution as well.

All of these issues may be workable for some people but many of them are blockers to even consider trying for others. I for one couldn't be bothered with that much hassle and would rather just play a newer game that doesn't have that BS to deal with. :) For the record, I'm experienced with using VPNs to do this also, so I don't balk at it out of inexperience but rather out of experience.

Added Spore Collection to the list/mix.

All of them? If not, can you be more specific as to which of them have serials?