StarCraft: Brood War/Terran Mission 3: Ruins of Tarsonis

Walkthrough
There are four hives in this mission, each with their own set of defenses, so you'll need a lot of variety in your army. You'll want to build up your army for the next hive while you're mopping up the previous hive. Fortunately, resources are plentiful. You have a nearby unclaimed mineral patch, and you can also loot the Zerg hives once you've destroyed them.

Defense isn't too tough, just add a bunker to the northwest to guard against purple's airdrops, scatter some missile turrets to ward off mutalisks, and put a siege tank at each end once you have a factory. Also build a comsat station and scan around to get an idea of how each hive is built.

The Brown hive is in the southeast. Build up a group of ten marines and two medics, and a group of twelve siege tanks (though you can do it with fewer tanks if you're impatient). Research the range upgrade for marines, and also stimpaks, since medics allow you to heal the damage from stims quickly. Park your siege tanks on the ridge above the hive, and rain down the fire. Use your stimmed marines to stop mutalisks and airdrops.

The next target is Purple, in the southwest. They are more air-focused, but you can use the same siege tanks and marines. Make sure your comsat station has full energy, otherwise build a few wraiths. Either way, park your tanks below the hive, reveal it with the comsat, and use your marines for air cover, just like before.

The top two zerg hives will now start sending raids at you. Red sends zerglings backed by ultralisks, while Orange sends mutalisks and guardians. To stop all of Red's attacks, just park your siege tanks at the north entrance and let them incinerate everything that comes near. For Orange, use wraiths or goliaths.

To take out red and stop the flow of ultralisks, build twelve wraiths. Fly straight at him, and you'll find he has no spore colonies and only a few hydralisks! You don't even have to cloak, just wipe the hive out from the air.

Orange has a pile of spore colonies, so you won't have much luck with an air assault (you can try anyway, to free up some supply). However, his guardians and mutalisks will quickly ruin your traditional siege tank/marine attack. Instead, use upgraded goliaths, which are unmatched in anti-air attack, to protect your siege tanks. Orange has almost no ground defenses, so just roll into the center of town, siege your tanks and destroy him. Then move Duran to the beacon to win.