Starcraft 2 Strategy & Walkthrough: Zero Hour (Hard) Achievement [VIDEO]

There are several ways to beat the mission and destroy the four Zerg hatcheries. Build three to four bunkers on the right and two to three on the left and use scvs to repair them. You also need at least three barracks to make marines and medics. You should have 1 medic per 4-10 marines. Defend the base as best as you can and rescue the remaining units. Mass up a lot of units and keep pumping marines.

Around 10-13 minutes into the game send your army to the southwest base (bottom left). You'll find three hatcheries. Move your units in and out to get rid of the Hydralisks and Mutalisks. Pull back when units rush towards you so you don't get attacked by spine crawlers. Destroy the Zerg hatcheries and leave the workers. They will rebuild the base. Move your units to the right wait or hide them until the workers rebuild the base then finish it off.

Timing is important. Don't send your troops in too late or you'll get massacred.

You can also attack the top right hatchery or a combination of both. Make sure you have enough units by the end of the mission. Don't forget about weapon and armor upgrades in the engineering bay.

Here are three videos to help you.

Source:

http://www.youtube.com/watch?v=mVLk64rrqo8&feature=related

http://www.youtube.com/watch?v=qvaPvnThCkM&feature=related

http://www.youtube.com/watch?v=mVLk64rrqo8