StarCraft/Terran mission 4: The Jacobs Installation

Since you've allied yourself with the Sons of Korhal 'terrorist' group, your tenure as Magistrate is suspended... a nice way of saying you're fired. The planet of Mar Sara is being overrun by Zerg forces, and both the Confederacy and the Sons of Korhal are evacuating the planet. However, Mengsk wants you and Raynor (whom he rescued from the Confederates as well) pick up some data discs from an installation before you leave.

This is the first of the three 'installation' missions in StarCraft. In these types of missions, you must wind through a maze-like path to get to the end. You cannot harvest resources or build a base; therefore, you don't get to build new units. Instead, the game will give you reinforcements at key points along the mission.
 * Walkthrough

Group all units including Raynor (who is a Marine this time) into one. Simply go along the path until it splits into three, taking out the easy-to-destroy wall turret en route. The path going southwest is a longer but resistance-free one, and northwest is a shortcut with resistance (ignore the northeast path, because it leads to a beacon transporting you to a useless spot). Pick either one. If you choose the shortcut, when you run into enemies focus fire on all units except the Goliath, and finish it off last. This is because it is the unit that takes the longest to destroy. Either path will eventually end up at the same spot, and a bit farther from there will take you to a place with another split path. Choose northwest and walk onto that beacon, which will unlock two doors containing Zerglings (for you to kill) and critters (for you to... well, do whatever you want with), and also some plot dialogue you'd otherwise miss. Now go back to the intersection, go southeast, and walk onto yet another beacon. Come back to the intersection and continue straight until you come to what seems like a dead end with a beacon. Well, since you have nothing else to do, walk onto that beacon and watch all your guys be teleported to another sector. From here, you just have to follow the path, annhilating resistance (using StimPacks if you have to). Walk onto yet another beacon at the end to complete the mission!