Changelog for update 1.26 / GOG-2 (Windows) (added 16 December 2015):

This patch is currently available on Windows only

- Added online multiplayer mode
- Fixed error on joining all servers for some players
- Fixed error at ending tutorial after dying 1 or 2 times
- Added message telling players to join servers in their country or near them

Any ETA on when the Mac and Linux versions are coming?

Nice, didn't think gog would recieve the patch after all that time ^^

Is it my imagination, or is the game running less smoothly after this release? :/

Has the 1.3 version been released on GOG?

Changelog for Internal Update / GOG-18779 (Windows) (added 14 March 2018):

- [WIN] updated internal installer structure, no changes to game files

Changelog for Patch 1.3 (added 11 July 2018):
[This is a Windows only update. The Mac and Linux versions will be updated as soon as possible]

- Now automatically switches to the dedicated graphics card over integrated - so if the game was running poorly on your gaming laptop, this could fix that
- Fixed a few problems with connecting to bad servers