http://hotfile.com/dl/54902321/7087ba7/Overrun_reaching_tier_3.SC2Replay.html
No one ever reaches at least wave 13 with me so here's a walkthrough
LEVEL LISTING AND WALKTHROUGH
W0 - build rax, 3 bunks, and 12 marines. BUILD THEM AS CLOSE TO THE CC AS POSSIBLE AND MAKE A WALL WITH THE BUNKS. Too many times I have seen people build their bunks out in the open. Walling them will make it harder for enemies to surround it, thus less damage is dealt
W1 Drones TIER 1
- build a bunk on 50 mins and wait until you get 3 rines before you fill it up. After the wave ends build a depot next to one of your bunks (we are making a wall, this is very important for tier 2) and make 1 more rine to fill up your fourth bunk.
W2 Broodlings
-Research trigger happy first then build a engineering bay. Once the wave ends transform your rax to whatever you want. I strongly recommend Hellions, they always work for me :D They have autoheal (so they can be left out in front) and upgrades affect them the most i think.
W3 Zerglings
-Research Neosteel Frame. Get 4 of your 1.5 units (maruads, hellions, etc). Bunk them up
W4 Roaches
-Research Weapons level 1 and then I got infernal pre-igniter. Get three more rines. Once the wave ends build a depot and get the last rine.
W5 Queens
- Research Armor level 1
W6 Super Broodlings (Tier 1.5)
- Research Weapons level 2. You don't have to now, but I researched autoheal for my hellions. Someone will usually die on this wave. Salvage any of their leftover buildings It's very important that you do this throughout the game whenever someone dies. Once wave ends, research Weapons level 3.
W7 Hydras
-Research Armor level 2. I started pumping out hellions for the next wave. Because blue died, I was allowed to get another bunk (5 bunks is necessary to make tier 2 easy) and another depot which finished my wall-off.
W8 Infestors
-Continue pumping out hellions until you reach 10 that is not bunked. Do not bunk any of them in the 5th bunker, just make a wall with them in front of your other bunks.
W9 Super Drones
-Do not make or research anything on this wave unless you need to replace one of your hellions. Save up for tier 2.
Wave 10 Nydus Worm Boss Round.
-Don't need make anything unless you lose a hellion. Micro your hellions around so that they are not surrounded. If the worm pop outs inside your base, do not move your hellions there, just stay outside. Don't worry, they won't attack any of your other buildings unless they're blocked off from attacking anything else If micro your hellions right, you won't lose any of them.
Before Wave 11
-You should have over 1000 minerals by now. Transform all your bunks in to super bunks, transform your rax into a facility and exchange all your tier 1 units. Evenly fill up your bunks with reapers, the end bunks being the most important. Oh btw, enemies won't attack dead players' lanes, so don't be afraid to build your buildings there if you run out of room.
Wave 11 DTs TIER 2
-This should be easy if you have five bunks. Continue filling up your bunks. Nydus Worms will continue popping up throughout tier 2 which spawn zerglings, roaches, and one super broodling at a time. They do not give you minerals and get stronger after each wave. If you get supply blocked, use the supply drop from the cc on one of your depots.
Wave 12 Archons
-Continue filling up your bunks with reaps and supply dropping your depots if you get supply blocked.
Wave 13 Mules
-This is a free round meant to prepare you for the incoming air units in the next wave. Mules don't attack so the only things that damage you are the ones that come out of the worms. Zerglings that spawn from the worms get their speed upgrade this wave i think.
After this wave, you'll need to get either stalkers or missile turrets. I recommend stalkers because missile turrets are terrible against the broodlords in wave 18. I was lucky that red quit with most of his stuff intact so I was able to get siege tanks as well.
Wave 14 Sentries and Mutas
-If you don't have siege tanks already, this is the wave to get some (you'll need to get another facility) because they are necessary for the next wave and especially wave 17. Make sure to balance tanks and stalkers because they are both necessary. Don't be afraid to leave your stalkers in front because ground units don't attack things that can't attack them Siege your tanks behind your wall.
Wave 15 Vikings
-If you have tanks already, this wave should be easy. This is why walling off is very important, because it prevents units from attacking your tanks. I also transformed my bay to an armory and got weapons level 1.
Wave 16 Probes and Phoenixes
-Continue pumping out Tanks and Stalks. Research the upgrades for the tanks and Stalkers.
Wave 17 High Templars and Banelings
-It is important that you don't let any of the banelings (which do 200 SPLASH damage) attack your bunks or you would die very quickly. Tanks make this wave easy. If you have spare units that you got from the dead players bring them out for just this wave to prevent the banes from reaching your bunks.
Wave 18 Broodlords
-This is the only air unit that has long range. If you have enough stalkers this should be easy. Continue pumping out stalkers and make sure not to have to many broodlords attack them at once, so micro them.
Wave 19 Banshees and Marauders
-This level was actually quite disappointing. If you have enough stalkers and tanks, you should be able to do this without sustaining virtually any damage. Just make sure you micro your stalkers because the banshees have a very short range. If you micro them right, you shouldn't get damaged. Research carbonsteel plating and fill up your bunks with reaps. I also researched weapons level 3 and armor level 1
Wave 20 Massive Overlord Boss Round
-A Massive Overlord would come out and hover above your CC. You cannot attack it. Wherever it shoots out his tentacles (which is marked by the green insignia beforehand), lots of units will spawn. It will spawn a mixture of mutas, banshees, marauders, archons, and HTs. You won't really need to pay much attention to your bunks but if you see one flaming, heal it. Continue pumping out stalkers (this is important) because air units will soon outnumber you. If you know too much air units have bunched up, use your overdrive. Have some stalkers guard your tanks because air units are bound to attack them. You would have to survive this for four minutes. After 1 minute, the ovie would start spawning 3 groups of enemies, and in the last 20 seconds, it would spawn four groups of enemies.
Wave 21+ Bonus Rounds.
-If you have reached this, you have finished! Well this version anyway. The maker hasn't made the third tier yet, so I regard these rounds as bonus rounds. In these rounds, hundreds and hundreds of tier 1 zerglings will continue to spawn. But if you have at least 6 tanks, you can do this infinitely. Btw, you can't make any tier three stuff so don't even bother unloading them. :D
Well I hope that this helps you :D
Couple of Notes:
-Don't forget to upgrade
-Walling off is IMPORTANT
-Make sure every bunker is inline with each other so maximum damage is dealt and minimum damage is received
-Build as close to your CC as you can
-Minimize the area that enemies can attack you from (build depots, wall off, etc)
-Hellions are better than marauders
-Micro your outside units
-Make sure to salvage what you can of the dead players
-Don't be afraid to build buildings in dead players' lanes, enemies won't attack them.
-Armory upgrades aren't needed in tier 2 until level 15
-You'll need AA by Wave 14
-Stalkers are better than Missile Turrets
-You'll need Tanks by Wave 15
-Almost all the air units have short range, so it is important to micro your stalkers
-Save up your overdrive until you actually need it. Don't be pressured to use yours because someone activates theirs. :D
-This is only one of the many lanes you can take. Feel free to experiment :D