TvZ is one of those iconic matchups that StarCraft players know and love. You have to really keep on your toes and stay aggressive if you are going to prevent the zerg from spiraling out of control and building up a massive economy. The nice part about TvZ is it does offer you a lot of opportunities to stay aggressive and be the attacking player so you will have a lot of opportunities to work on your micro and multitasking.
Generally the strongest opening is to start with a depot, then refinery, then barracks and finally make another command center on the low ground. You will want to build a reaper right away in order to scout or fend off any early harassment zerglings and then usually you are going to want to follow up with a factory and a reactor for your barracks so that you can swap the barracks and the factor and start pumping hellions right away two at a time.
Now there are some other strategies you can try as well, for example building two or three barracks near your opponent’s base and trying to deny their fast expansion with your marines and a few bunkers, but any cheese play like this is a bit of a gamble at the best of times. In the long run, the percentage play is going to be to do a safe macro style and try to build up your economy. As soon as your barracks finishes you are going to want to morph your command center into an orbital so you can have that lucrative mule income. Your first three command centers should be morphed into orbitals and then after that, you will want to make planetaries to give your most vulnerable expansions a little extra tanking power.
There are a couple of strong attacking options in the early game. You can do a hellion run by right away with your first two but it’s usually better to wait until you have four hellions and then you can really start roasting up some drones. You can also try a quick hellbat push on your opponent’s third base, or just do some drop play. Getting a viking early on after your first medivac is a nice way to start clearing up overlords and denying your opponent that all important scouting information. Even if you can’t find any damage with your hellions you can at least use them to prevent creep spread and to keep tabs on your opponent’s troop movements.
Widow mine drops aren’t quite as op as they used to be, but they can still do a lot of damage if you catch your opponent unprepared. Another powerful early game attack is to try for a double drop stim timing. Drop play is very strong in TvZ and you can also try queueing up liberators so that they attack at the same time as your drop. By hitting multiple places at once you can really do a lot of damage and it is very difficult for your opponent to fend off this sort of play.
You will want to watch out for any sort of early game aggression like a roach ravager all in on the part of your opponent, which does have the potential to be game ending if you don’t catch it in time. The good news is that if you can fight off this attack then you will be in good shape because your opponent will have sacrificed heavily on his economy in order to build these early units. Bunkers, cyclones, and timely scv pulls are the best approach to fending off a menacing roach horde.
Another powerful opening is to play a bit more of a defensive macro style and just throw down a third command center right away. You don’t have to fly it off immediately, you can just drop its mules and build some scvs out of it right away if you feel like it might be too vulnerable at your third base.
During midgame TvZ you want to build up a massive marine / maurader / tank / medivac force and then as you approach the late game start adding in liberators and ghosts. Your mauraders are going to be great for soaking up baneling hits, so whenever possible leave these guys in front and micro away your marines. Tanks are a very powerful unit and can be used to siege up against a base from a distance. If the map you are playing on has some terrain that can be abused then so much the better. Liberators are useful harass units through the mid game, and you can still do drops as well. Drops can be a good way to pull the zerg’s army out of position, enabling you to set up close to one of their bases and start pounding away.
You will want to use supply depots to wall off your bases and slow down ling or baneling runbys. Upgrades are very important and the longer the game goes on the more damaging an upgrade deficit will be, so make sure to get double ebay early on and stay on top of these upgrades. You also have the option of going mech, which means that you build a bunch of factories and produce only tanks, hellions, thors and starport units as well such as ravens or vikings. There are a lot of different flavours of mech. You can go “battle mech” which is mostly hellions and cyclones and usually has a very strong map presence during the early-midgame or you can do more of a turtle style where you build up a massive tank/hellion/thor army and then push out with near max supply.
The thing about turtle mech is if your massive tank army does get wiped out it will take forever to replace, so you have to be very careful about how you engage and make sure that you are not just throwing units away. Thor drops or double thor drops are always fun and can do a ton of damage before they are finally chased away, but make sure not to lose your medivacs or your poor Thors will be stranded in enemy territory and they are not exactly a high mobility unit. Hellion run-bys are a mainstay of mech play and you do want to make sure you have the right balance of tech labs and reactor cores to ensure that you can spend all of your minerals and vespean appropriately.
While your first command centers need to be morphed into orbitals in order to get a solid economy at the start, as the game progresses you can make your outermost bases into planetary fortresses in order to give them the ability to withstand smaller attacks. While not invulnerable planetary fortresses are very effective at stopping ling run bys and can even hold off larger armies while your troops rotate around to defend the base.
During the late game, you are going to want to tech up to liberators and liberator range if you haven’t done so already so that you do have an answer to ultralisks. Ghosts are also great at sniping down these lumbering behemoths. If your opponent chooses to opt for broodlords or switch into this tech then you will need an answer for those as well, probably in the form of vikings produced out of double reactor starports. Getting a solid tank mass can be very useful as well because there is a tipping point after which it becomes almost impossible to attack into spread apart sieged tanks. If you do opt for a mech style, then complementing your army with ravens can make a stronger and more cost efficient composition and you will want to trade out your hellions with run-bys so that you can make stronger and more durable units like tanks and thors.
Make sure to stay on top of your expansions or your opponent will just trade against you inefficiently and starve you to death. Continue to use drops or small strike forces to deny morphing bases and pull your opponents troops out of position. You are also going to want to continue to push and try to wipe out some of your opponents bases with your main force if at all possible. Even just setting up near a base and then shelling the mineral line with tanks from the low ground can be a decent win. You always need to be mindful of where you are engaging and try to use the terrain of the map to your advantage by camping in choke points and preventing your opponent from getting a full surround.