Alliance are a serie of different mods. On the Star Wars GC, you can play the civil war Empire vs Rebel era + Black Sun and soon the Republic and CIS.
Here you can see some more of the last Sabaoth Squadron units, the most relevant addition from the last update.
This is the main list of changes:
-Improved some particles effects.
-Improved space battles IA.
-Gargantuan hardpoints can not be destroyed anymore.
-KorribanK ground map sky improved.
-Engineers and MDU ground companies have a population value zero.
-Fixed Imperial mix infantry unit 2.
-Fixed hidden Anakin ISD Solo upgraded.
-Fixed Stormtrooper EWeb animation.
-Fixed Black Fleet GC heroes controlled by the AI.
-Land base Missile Tower can not target air units anymore. At least not all controlled by the AI.
-Special AT-AA firing blue shots adds heavier armor.
-Improved ATSTAP AA Walker AA weapons.
-Fixed missing units RB Rebel Regiments.
-ATST Improved.
-ATST AS Improved.
-Bastion space map improved.
-SPMAT and other artillery ground units, fire range increased.
-AV7 Clon Gun improved.
-Ground artillery impacts improved.
-Fixed Imperial Golan sold.
-Improved Xwing colors.
-Improved ground Xwing engines.
-Added CIS Gunship Death animation.
-Added Saboath Carrier and Destroyer.
-Improved Saboath Fighter.
-Added Saboath Hex Deployer.
-Improved Imperial Explosions Huge.
-Chain explosions improved.
-REBELSMOKEDEATH improved.
-IMPERIAL_MIDSHIPSMOKE improved.
-Krayt/Fel Eweb animations.
-T1B size Red and Green proyectile improved.
-Garrison Artillery turret capturable by Krayt/Fel in some ground maps.