straight from the sierra stratigy guides
The challenge here is to fend off the attacking Plymouth units while accumulating enough Metals to complete the mission. Attacks come from the four corners of the map, sometimes from two directions at once. Each attack will consist of two to six units, so be prepared to build several groups of eight Lynx for defense.
Start all five Cargo Trucks on an ore-hauling route between the southern Mine and the Common Ore Smelter. Bulldoze a double-wide path to the Mine to decrease travel time. When the mine yield on this mine drops to 240, move your cargo trucks to service the mine located to the west of the original mine. Build Rail Gun Lynx immediately. After you have 12 or so, build additional Cargo Trucks and start an ore-hauling route between the Rare Ore Mine in the southwest and the Rare Ore Smelter.
When you build the Guard Posts that are in the ConVecs, connect them to the base with Tubes to maximize their effectiveness. You can defend the northeastern approach with three Guard Postss and two Rail Gun vehicles. Place an additional Guard Post to defend the southwestern approach in conjunction with a group of eight Lynx to be shuttled between the southwestern and northwestern approaches. Place the remaining Guard Posts near the southern mine, along with another group of six to eight Lynx. Always repair damaged Guard Posts immediately after each attack. You have a ConVec for each, so there is no shortage of vehicles to repair them.
Having several combat units in reserve allows you to cycle damaged vehicles to the Garage for repair between attacks while maintaining the integrity of your defense. It is faster and cheaper to repair them than to build replacements.
If you lose one of your Tokamaks, build a GeoCon and tap either of the fumaroles in your base.
