The Autobots have just opened their Energon Mine and are preparing to transport the first cargo when the Decepticons attack, intent on stealing the energon!
Optimus Prime repels the Decepticon forces using the missile launcher at their nearby base. You can control its inclination and velocity of fire, so it's a ballistics game. Hit the demolished transport, and it explodes, destroying the mine. Hit the mine 3 times, and it goes boom.
Decepticon Scouts fly up to the wrecker transport and lower grappling claws to steal 5 energon cubes at a time. They are the first Decepticon adversary you face and easily destroyed. If they encounter no resistance, no other classes of troops will appear, and Scouts will continue to raid until they have stolen 100 energon cubes.
The drill-handed "miners" follow the Scouts. Utilizing the Autobots' cargo elevator system, they drop below the mine and tunnel up into it, stealing 5 energon cubes at a time. Miners can only be destroyed while above ground, requiring you to lob the missiles over the energon mine to hit them outside of the cargo elevator.
The raiders are extremely difficult to hit. Breaking across the open ground in their high-speed gun-tank mode, they transform into robot mode and scramble over the top of the energon mine, making them very dangerous targets. They steal 5 energon cubes at a time from the damaged transport. Raiders will be destroyed by a direct missile strike, but if you miss, you may destroy the mine itself!
Decepticon jets travel at very high speed, scouting the Autobot base from a distance before performing a radical aerobrake maneuver to drop like a stone while transforming and snatch 5 energon cubes from the damaged transport before transforming and jetting away. They are extremely difficult to hit.