I managed to do it with just Marines, Medics, Marauders and Siege Tanks.
I put up two bunkers and four tanks at each ramp for defense, then built up my forces for the assault.
I attacked the base directly to the north.
The initial tactic is to place tanks in siege mode a little bit back from the protoss ramp so they are out of range of photon cannons.
Then run your MMM ball halfway up the ramp
so the tanks can start shooting down the cannons.
Meanwhile keep the drill hotkeyed so that it can assist in taking down archons, collossi, void rays, and anything that's doing damage.
Don't let your MMM ball run out of reach of your tanks.
When you've beaten back their initial defensive line you've got a foothold.
Move your tanks up and keep on pressing in.
Focus on taking down the pylons around unit producing buildings and keep your drill handy to zap the occasional pylon or counter-attacking heavy unit.
The real key to this strategy is you need to keep reinforcing.
Keep your barracks and factory hotkeyed and move the rally point to deliver troops near the front as you move from left to right across the map.
Before you've taken out the entire northern base you should have the achievement.
Good luck!
gaming.stackexchange.com/users/304/JavadocMD
There are alternative strategies listed here : using ghosts on the cliffs and pick off buildings with the drill using floating buildings to allow siege tanks to fire on the high ground on the northern base, continue with infantry support
gaming.stackexchange.com/users/254/gfr
The key is to, expand, wait, get a huge army and then make sure you get a foothold up the north ramp.
Start by getting at least two tanks and one bunker with 2 marine 1 marauder per ramp.
Prioritize making SCVs.
When you have your initial defense up start expanding, move your south bunker down, pretty far back, the longer the tanks up on the cliff can fire on the enemy before reaching the bunker the better.
When you have your expansion up make an additional factory and two barracks (make some turrets so you don't have to worry about voidrays killing off tanks
bevause your marines are out of position).
From there just start massing units to the north.
Marines, marauders and tanks.
When the drill has gotten to the last 1/5th of the door it's time to move out.
Position your tanks in siege mode below the ramp.
Move up the ramp and start blasting.
Focus the drill on the colossi as they will eat up your infantry.
You need to keep making units and rally them to the ramp.
If you lose your foothold on the top of the ramp you will have to mass up units again.
Once you have settled in on the top of the ramp, start leapfrogging your tanks and blast any buildings and units with the drill.
Once you get rolling you will probably be able to take out every protoss building before the drill is even finished.
gaming.stackexchange.com/users/2872/Odge
I did it with a few floating barracks for spotting, and the drill to take down the buildings.
Keep the floating buildings on high ground, so that they can't be seen from the ground and slowly move in and take everything you see out with the drill.
Target any air units first, and then everything that can shoot up.
Whenever nothing dangerous is around, take down other buildings.
gaming.stackexchange.com/users/2765/sth
I got 25 barracks, and floated over the protoss base with 37500 hit points at my leisure and shift-queued the laser to take out all the buildings I could see.
I ended up losing a lot of barracks, but I had such an absurd amount that it didn't matter.
gaming.stackexchange.com/users/6655/recursive
I got the achievement with a safe but somewhat boring and slow strategy:
Turtle up with a boatload of siege tanks and missile turrets, and float a command center up to the northwest corner of the map to get vision on the Protoss buildings.
Use the cannon to pick off the buildings (and the defending units), stopping to take out the archons/immortals/colossi that gather outside your base when they appear.
Your tanks can handle zealots and stalkers, so don't waste cannon time on those.
The Protoss will continually rebuild the structures that you destroy, so you can probably just work your way back and forth in the top-left area of the map until you've blown up enough structures to unlock the achievement.
Try building two command centres, and bring one back to base for repairs when it gets heavily damaged.
When controlling the cannon, remember to use the Shift key to queue up multiple targets.
This will give you a few seconds to do other stuff around your base while you wait for the cannon.
When scouting structures with your CC, you can use the Hold Position ( H ) command to stop it from moving around when taking hits and losing vision on buildings at the edge of the fog of war.
I'm sure other methods will get the job done faster, but this strategy was very safe and not very difficult.
gaming.stackexchange.com/users/274/Brant
A key thing to remember with this sort of mission is that you can get the achievement even if you fail the mission .
So feel free to do an all-or-nothing blitz to kill their base, while doing only the minimum to secure your own.
Once you kill 50 buildings, you can restart it and finish it cleanly, or just restore to a save.
gaming.stackexchange.com/users/479/Satanicpuppy
The title pretty much sums it up. I am replaying some missions in Hard mode to complete achievements, and I am stuck with this one ( "The Dig"  mission in Hard mode).  I watched this video series:    . That strategy with Vikings seems nice, but I played this mission without unlocking Vikings first. Has anyone completed this achievement without Vikings and would have a nice strategy?
How can I complete the "Yippee-ki-yay..." achievement from "The Dig" mission in Starcraft 2 without Vikings?
gaming.stackexchange.com
<starcraft-2><achievements>
gaming.stackexchange.com/questions/5355
gaming.stackexchange.com/users/2320/sirdharma
Place tanks in siege mode, wait, get a huge army and then make sure you have a foothold up the north ramp.  There are three main tactics you can use, initially place tanks in siege mode behind the protoss ramp. Then expand, wait and get a huge army, mainly siege tanks and missile turrets.
Three tactics are put forward by users in answer to this question.