StarCraft: Brood War/Terran Mission 4: Assault on Korhal

Walkthrough
Both targets are equally well-defended, but your choice will affect the start of the next mission, as the weapon you don't destroy will be used against you. Your base has no less than four routes into it, and you will face a vicious ground assault through all of them. Quickly put up bunkers, missile turrets, and a siege tank at each entrance.

There's an expansion to the West of your base on a cliff. It's not defended, and the only force that would come there are a few enemy patrols, mostly Marines. If you expand early, you can prevent the enemy from setting up a force there, gain yourself an early economy, and make the rest of this mission much easier. If you don't, the enemy will set up a defensive line on top of the cliff, which will have a Siege Tank and a few other units that will be more of a nuisance every time they go down that ramp. So, expand West early and get moving!

You may find it useful to expand East to claim extra resources. This will also give you more room to build your base, as you will find the starting location a bit cramped by the time you're finished. Even the clifftop is very small to make a sizable force, so it is recommended to expand East. The downside is that you have twice as much area to defend (this Eastern area takes up the right half of the map), but it provides good choke points to make this easier. Having a second (or even third!) command center also allows the use of Nukes! If a group of enemies seems tough to crack, drop a nuke on it before rushing in.

The attacks will start small, but hit hard later on while you're trying to build an army. Siege tanks will make scrap of your bunkers without an SCV actively repairing, and the enemy is smart enough to park them outside your vision and use spotters. Ghosts will lock down your tanks and cloak when you shoot them, so you'll need missile turrets to detect them (and later, science vessels), and medics to restore the lockdown before they're destroyed. Finally, the enemy will add marines, vultures and goliaths to mix things up, but your bunkers will beat them easily.

Once your base is secure, it's time to build your army! There are plenty of missile turrets around the targets and the enemy has a ComSat, so Wraiths probably won't cut it. Siege Tanks are the backbone of your force. Bring a group or two of marines and medics to provide air cover and Restorations, a couple SCVs for repairs, and a Science Vessel or two for spotting. Both targets have a choke point where your siege tanks will be bottled up, but if you lead the charge with some stimmed marines and medics, you should be able to break through. Then, just leapfrog your siege tanks forward, park in the middle of their factories/barracks/starports, and blast everything in sight. Watch out for enemy dropships, but 12 siege tanks should be able to destroy anything before it gets close.