From FreeSpace Wiki
Merkar is a out of universe campaign.
The FSCRP has released an upgrade of this campaign.
Mods: Lots of new ships
Missions: 4 in the demo
Projected release date: Never, ever
The Merkar Demo is a four mission campaign released in 2010. It covers the beginnings of the Spaceborne Army of Merkar. The first chapter of the full mod may be released at a later date.
The Merkar Demo received mixed reviews. Some liked the unique features present in the campaign while many found it buggy and in need of playtesting. A patch was released to address some of these concerns; the link below includes the latest patch.
The Restored version at FreeSpace Mods: http://freespacemods.net/download.php?view.665