Alien Walkthrough: A1
A1. Explorers Uncover Dormant Hive
Years before the human development of LV-742, a routine Weyland-Yutani probe indicated the planet to be rich in mineral ore.
Shortly thereafter, a team of explorers and engineers arrived with a modest USCM escort to verify the probe's findings.
The explorers conducted seismic drillings and extracted core samples.
One drilling site opened up a cave that housed a cache of Alien Eggs.
And now, the explorers further investigate their new discovery.
Human explorers have opened the cave containing your Eggs. Now is the time to breed, and grow, and dominate. Use a Praetorian Egg to create a Queen, then grow the Hive, spread the horde, and kill the Marines in their northern base; its marked on your mini-map. During the mission, your objectives appear in the pause menu, which may be accessed at any time by pressing the start button.
REVIVE THE HIVE
Objectives:
* Create a Queen.
* Destroy the Marines in the camp to the northwest.
Optional Objectives:
N/A
Starting Forces:
* 500 Infestation Points
* 1 Drone
* 7 Eggs
* 1 Praetorian Egg
Target Time: 12 minutes

Open up three of your Eggs and send the Facehuggers south quickly. There are three Explorers to the south, and they are civilians so they won't harm you. While your Aliens are growing into adults, send your Drone down to meet them. You'll now have a Drone and three Warriors.
Send your four Aliens west. This next area is filled with civilians, but there are also three Infantry to the west. You should be able to kill them without any losses. Work on killing the Explorers in this area so they don't run around, and hatch your remaining four Eggs, sending the Facehuggers to impregnate the civilians. Now hatch your Praetorian Egg. In the area with the Infantry and Explorers, there are some Oswocs to the south. Have the Praetorian Facehugger impregnate an Oswoc, as you want to save your supply of humans for transbreed Aliens. When you have your new Praetorian, have it move to the center of some comatose humans and transform it into a Queen. Then create her egg sac. Assign your one Drone to moving Eggs.
Get the Drone upgrade as soon as you can. If there are civilians left, kill them with Drones to produce some Cystic Warriors. Keep making more Aliens in this area. Make sure you make a few Drones using the Oswocs as well. Wait until you have an army of about 25-30 Aliens, consisting mostly of Warriors, with a few Drones. Leave your Queen with a Warrior and the egg moving Drone for protection, and send the rest of your forces west. You'll encounter some Infantry. Past them, there is a Marine base to the northwest, so head that way and slaughter any Infantry and Synthetics you find. North of here there is another Marine base, and destroy that one as well.
Head straight north all the way, then head west. This is the Marine base, as marked on the map. Casualties don't matter at this point, so just go all out and attack like crazy. Enter it and kill all the Marines inside to complete the level.
A2 --->