What is a strategy to earn the best defense achievement in StarCraft 2?

Question

I have been attempting to earn the Best Defense achievement in StarCraft 2.

The Best Defense is an achievement earned during the third mission of the Wings of Liberty campaign: Zero Hour. The goal of the mission is merely to survive 20 minutes, while awaiting evacuation. However, the achievement is earned by destroying 4 Zerg hatcheries during those 20 minutes.

Thus far my strategies to accomplish this goal have failed. Has anyone devised a winning strategy to earn the achievement?

Answer 1

Build a refinery first, then add a bunker next to each of the existing ones by the bridges. Build a billion SCV's , a billion supply depots, and 4 barracks (one with tech and 3 with reactors). Tech barrack should only produce medics other three should only produce marines. Don't worry about stranded rebels, keep all troops near bunkers until about 9 minutes are left. Attack the Zerg base at the top left of the map with a force of about 30 marines. concentrate fire on Zerg troops until there are none then have half the marines fire at each hatchery. THE MOMENT you have destroyed BOTH hatcheries, immediately pull your troops out into the corner away from the Zerg base, do not destroy anything further. Keep building troops and after a few minutes send a second force of roughly 20 or so troops to meet up with the first force. The hatcheries should have respawned by now and you can go in and destroy them both with little resistence a second time to earn the achievement.

Answer 2

This isn't an easy one to earn. It requires decent micro of your troops, while still focusing on the macro of getting more troops. There isn't much more to say besides "play well", but I'll give a couple of general strategy hints:

Get an SCV or two out by your front line to help with repairs. You should also be able to easily get the "don't lose a building" achievement at the same time.

Get 3 SCVs on each minerals. Get those minerals coming in as fast as you can.

You might discover that money is coming in faster than you're spending it, get another barracks to pump out more troops.

One of your barracks should have a reactor core, and the other a tech lab. 2 marines per medic. As soon as you've got a decent force, (which should probably be < 5 minutes), head out. I'd recommend going around the map in a counter-clockwise fashion, i.e. head out north east, rescue the first group of trapped units, then head in the general direction towards the second group of units, then the third, killing all Zerg along the way. New troops that you make should head to your group soon.

The enemy gets stronger as the time progresses, so the sooner you leave the better.

Answer 3

Hmmm. This is nothing like how I did it (didn't realize the hatcheries would respawn), but I'm not sure my method is the "best" method.

I pushed hard and took out the two hatcheries at the northwestern zerg base at around the 7-8 minute mark. If you get them that early, they're pretty weak. You need to make a strong effort to "save" the groups of medics and marines that pop up, and keep your troops out of the way of the random spawn waves...I walled off with depots, and used the mobile force to take down the waves.

Hitting the near left base after the 10 minute mark is not easy; you'll have a lot more troops to fight off, and your micro will need to be very solid. And it's a given that your main base WILL NOT SURVIVE so you're going to lose the mission. But there are two hatcheries there, which will take you to 4 killed.

Here's the kicker: if you kill the hatcheries, you'll get the achievement whether you win the mission or not. So if you're having trouble doing it as stated above, try it this way.

Answer 4

If you don't care about the 'No buildings lost' achievement, I have an alternative strategy that is more of a macro approach than one that requires more micro, and is generally easier to pull off in my opinion.

The crux of the plan is to pull back from the bridges and hold the ramp until halfway through the mission. A more detailed guide will follow, but the key points are:

• Salvage the bridge bunkers at the start for extra minerals
• Double Reactor; build Marines non-stop (yeah, no Medics. I can hear your cries of indignation already :P)
• Build a third bunker in the gap between the two ramp bunkers, and leave an SCV or two on repair duty.
• As you begin to have more resources than sense needed, build a third Barracks with a third Reactor to keep up production.
• Get +1 to weapons before moving out.
• Around the 10 minute mark you should have around 100 supply of Marines. Push out and up the left ramp towards the western zerg base (3 hatcheries) and then further up the left road to the north-western base (4th hatchery).

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Mission Start:

• Salvage the bottom two bunkers near the bridges, and put the marines in the bunkers up the ramp.
  • Tychus will pipe up about getting 'tore up out there' as the bunkers destroy themselves.
• Get your SCVs mining (minerals only) and queue up a few more at the Command Centre.
• Build Reactors on your Barracks.

Get the Mineral/Gas crates

• Once you've got all Marines together, don't fill the bunkers, but push out towards where the rebels will spawn along the road to the right, using Attack+Move.
• On the way there, 2 groups of Zerglings/Hydralisk will unburrow and attack you. You shouldn't lose any Marines, but move the damaged one(s) to the back of the group after the first attack.
• Climb the ramp and grab the Mineral/Gas drop.
  • Use the 100/100 to start Marine Attack Upgrade +1 at the Engineering bay
  • Your Reactors should be done about now as well, queue up some Marines and get an SCV building Supply Depots as well. (You should continue to build SCVs, I'm going to stop mentioning it at this point)

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Optional - Marine Group #1

• This isn't really optional if you went to get the resources. Just do it.
• Leave a Marine at the top of the ramp. This will allow you to collect the rebels later. Put him towards the back and use 'H' to put him in hold stance. He won't be noticed by the zerg and won't aggro them this way either.
• This is the easiest way to score 6 free marines, and definitely the easiest group to get, as once they spawn you can literally walk them back to base without Zerg interference.

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Hold the line

• Send the rest of the Marines back to base, and put them in the bunkers at the top of the ramp.
• Get an SCV to build a third bunker in the middle of the other two, effectively blocking off the ramp.
• Continue to produce SCVs, Marines and Supply Depots.
• As you might've guessed, this is a very Minerals-heavy strategy. At about the 14-15 SCV-on-minerals count, put one SCV on Gas. Once you have enough to earn Armour +1, put him back on Minerals.

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Optional - Marine Group #2

This is the hardest group to get.

• After the first push to get the Mineral/Gas crates, take the initial Marines on one last outing, up the left bridge towards where the middle group of rebels will spawn.
  • Don't take the outside road path as it's too risky & too full of enemy units, you'll take too long getting past them. Go back past your base and cross the bridge again.
• Grab the Mineral/Gas crates here as well, you can use the Gas to get +1 Armour
• Don't leave a Marine here - At some point the Zerg will send Mutalisks directly over this area and will take out your Marine before the Rebels spawn.
• Later
  • When the group spawns, empty your 3 ramp bunkers forwards, and use this group to push to the Marines/Medic,
  • Fill up the bunkers again from the Marines you've been building behind it.
• Be careful on your return journey, a push seems to come from the western base just as you pick them up - best to wait until they pass.

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Push out

• At around the 10 minute mark, (as Raynor pipes up), empty your middle bunker and salvage it. Once it's done salvaging, empty the other bunkers, control group every marine you have and start attack-walking up the left bridge.
  • Set your Barracks to rally on the remaining bunkers, and possibly get an SCV to rebuild the middle one
• Keep a wall of Marines up front of the group, don't let them enter single-file. Keep pushing up and left towards the western base

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Optional - Marine Group #3

• They should appear just as you're beginning your push to the hatcheries, send a Marine up the ramp to collect them as you waltz past.

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Hatcheries 1,2 and 3

• Push your Marines up the ramp, using the Move forward,Attack-Move, Move Forward, Attack-Move to keep gaining ground. Focus down the Nydus Wurm to the left and the Spine Crawlers protecting the ramp.
• There are 3 Hatcheries up here. Focus them down one by one, making sure to attack-move every now and then to take out defending units, especially the broodlings that spawn from destroyed buildings.
• Once all 3 hatcheries have fallen, back out of the base quickly.

Hatchery 4

• Once down the ramp, take out any aggro'd units following you and start pushing toward the north-western base.
  • It might be a good idea to empty your bunkers again and start pushing those units up toward the main group if you don't think you have enough to take out the 4th hatchery. If you do this, take the main group down towards the fresh marines as well so they don't get ambushed as easily.
• Make your push, taking out the mutas, hydras and Spine Crawlers that come to defend the hatchery.

Endgame

• Once it's destroyed, pull back to your base with any remaining Marines. You should be able to hold without them, but they will be useful if you can get them back.
• You don't need to complete the mission to earn the achievement, but in case you do, you only really need one surviving building to win the mission, so towards the end if you start getting overrun just liftoff your Command Centre and fly it to the bottom corner. hopefully the mutas don't find it until the timer runs out.

Answer 5

I didn't have enough of an army to finish off more than 1 sector of hatcheries, so I changed it up and attacked the 3 in the southwest first. This allowed me to reinforce my army with backup troops by the time the hatcheries were clear, and mega steamroll the ones in the topleft of the map with the combined forces. I actually cleared the mission too!

Answer 6

Dave's answer is probably the best. Build 3 groups of marines/medics and attack the top left zerg base. There are 2 hatcheries there. Concentrate fire on the two hatcheries and pull out of sight. Wait a min or two and go in again to kill the respawned hatcheries. Attack any of the other zerg bases and you will find yourself wiped out easily.