B E T A 3: H O L D A T A L L C O S T S
H O L D T H E F O R T !
There's little time to prepare for this mission. The Collective attack starts right away. All of the attacks will come from the north, so form your units in a line protecting the northern gate and prevent the enemy from getting around your right flank. You have very little power to produce new heavy units, so send your damaged units back to the Repair Facility. To conserve power, forget about doing any research at this time. Spend all your power on repairs and new units.
Use the trucks to constantly repair damaged structures before they can be destroyed and also to build new defenses. The enemy VTOLs wreak havoc on your base. They always attack from the same direction[Em]northwest. Therefore, build several AA Sites northwest of your base. They'll shoot down most of the VTOLs before they can make their attack runs against your base.
If you still have a Mortar group, move it to the area southeast of your base and out of danger. Although you could use it to help for defense, the VTOLs and other enemy units will decimate it. Besides, you need the Mortars for the offensive phase of the mission.
T A K E T H E F I G H T T O T H E E N E M Y
After several assaults on your base, the enemy's attacks will start to die down for a bit. It's time to begin your offensive. Send a group north to locate the enemy base. To help clear the line of sight for your units, attack the ruined buildings in your path and bring them crashing down. To the north, you'll find the first Collective base. Don't attack it with your combat groups. Instead, bring up your Mortars. Move them along the western map edge, and attack the western side of the enemy base first. Keep a combat group close by for protection against enemy counterattacks. The Collective's VTOLs love to attack your Mortars, so bring four or five AA units and position them northeast of the Mortars. It's also a good idea to bring a Repair unit or two along to fix any damage during the bombardment.
After leveling the first base, take some time to repair damaged units and replace your losses. The enemy base you just destroyed contains two Power Sources, so build Oil Rigs over them, and also build a new Power Generator either here or at your main base. Once you're ready to renew the attack, order your units to head north. The Collective has a small base on a hill in the northeast. Take out the defenses, then destroy the two Cyborg Factories and the Command Center. Send a combat group around the right side of the hill to take out the Mortar Pits and bunkers behind the hill.
The main Collective base is best of the Cyborg base. Take out the defenses at the base of the hill, then wipe out all of the structures on top. However, leave at least one of the hardpoints along the western edge of the map. Since this mission does not have a time limit, you can use this quiet time to prepare for future missions.