Vulture

Just research spider mines and litter the map with the little boogers. It'll annoy the heck out of your enemy and take out some guys. Otherwise vultures are pretty bad.

Hit Points: 80

Cost: 75/0

Damage: 20

Armor: 0

Upgrades:
- Ion Thrusters (increase Vulture movement speed)
- Spider Mines (enables placement of Spider Mines)

Siege Tank

Tanks must be made and siege mode must be researched as soon as possible. They're good for base defense and the last stage of an attack, but they need backup. A good mixture of Firebats and Marines should do the trick.

Hit Points: 150

Cost: 150/100

Damage: 30 (70 in Siege Mode)

Armor: 1

Upgrades:
- Siege Mode (enables Siege Mode ability, which transforms the tank into a stationary cannon)

Goliath

As you begin making Siege Tanks, you'll also want to make Goliaths. They'll pretty much replace your Marines. Three times the health... twice the damage.

Hit Points: 125

Cost: 100/50

Damage (Ground/Air): 12/10

Armor: 1

Upgrades:
- Charon Boosters (increase Goliath air attack range)

Wraith

If you're an air type of guy, get three or four Starports and pump Wraith's out like there's no tomorrow. And while you're at it, research Cloaking Field. Two squads of Wraiths are very powerful... but I probably don't even have to tell you that.

Hit Points: 120

Cost: 150/100

Damage (Ground/Air): 8/20

Armor: 0

Upgrades:
- Cloaking Field (enables Cloaking Field ability, which makes the Wraith invisible while depleting energy)
- Apollo Reactor (increase maximum energy)

Dropship

Get a couple Dropships, put some Tanks in, fly over to an unsuspecting enemy's mineral field... many explosions.

Hit Points: 150

Cost: 100/100

Damage: 0

Armor: 1

Upgrades: None