StarCraft: Brood War/Protoss Mission 2: Dunes of Shakuras

Establish a Base
You start with a few probes and some ground troops. Head west, dealing with a few burrowed Zerg, and build your base. As soon as you build your base, some hydralisks will pop out, but the Dark Templar will deal with them for you. That's one objective out of the way! Anyway, build some Photon Cannons at the top of the ramp to the south, which is the only entrance to your base, and later a shield battery. The path beyond has alternating Spore and Sunken Colonies, with the occasional burrowed Zerg. Your Dark Templars should get busy destroying these, since they won't be spotted except by the defenseless Spore Colonies. However, as soon as an enemy Overlord shows up, fall back until you have a bigger army. However you choose to clear these out, south of your base has a good expansion, and east of it is the main Zerg base. Start climbing the tech tree. It's not necessary by any means, but securing the bridge near the warp gate will let you use the entire center of the map as a staging area.

Destroy the Zerg Base
First, scout their base with observers so you know what you're up against.

You can approach this by ground or by air, or by a combination. By ground, you will have to destroy the line of Sunken and Spore colonies (Dark Templar will be useful again), and once you enter the main base, you'll be swarmed by all the ground troops the enemy can muster. A balanced force of Dragoons, Zealots, and Reavers should be able to break through. Reavers can take out static defenses, Dragoons are good all-rounders, and Zealots will protect them from Zerglings and are good at razing buildings. The enemy hatchery will continue to pump out units, but if you destroy their tech buildings (Spawning Pool, Hydralisk Den, etc.) you can cut down on their options.

From the air, you have to contend with Spore Colonies, but you will be able to strike directly at the enemy Hatchery and avoid Zerglings altogether. Scouts aren't very powerful when attacking the ground, but a full group can break through. Also, destroying a few of the Spore Colonies opens them up to the classic Reaver Drop. Take a few shuttles and load them with fully-stocked Reavers. Drop them all right next to the Hatchery and pummel it with scarabs. You'll probably lose your reavers, but you'll put a halt to their production for a while, and probably lower the local Hydralisk population.

Even if you lose your attack force, don't give up! You have extra resources to spare in the southwest expansion, so rebuild. Once you've softened them up, your second assault will be much easier.