They Are Billions – Strategy Guide to Buildings Units and Defense

They Are Billions - Strategy Guide to Buildings Units and Defense
They Are Billions - Strategy Guide to Buildings Units and Defense

Welcome to comprehensive guide to buildings units and defense.
You’ll find tips and hints here along with general useful things to know about.


So Lets try to cover some more important parts of using buildings in this game. Here’s a list of things that should improve your gameplay and be helpful to newcomers.

General Building Strategy Tips:

  • Plan ahead your warehouse, bank or any other “buff structure” and avoid building anything over that spot. 
  • Try your very best not to build over green land, so you get more use out of food. Same applies to quarry spots. 
  • Avoid placing houses near the walls as this will block you from building another one next to it, as they will not have a “door” out. 
  • Place the farms and quarry’s in a way where you get “more of them”, don’t look for the highest number as typically you get less income that way by the end of the day. 
  • Remember that buff structures such as banks and etc.. don’t stack on the same building. They are only affected by the bonus ONCE. 
  • Try leaving gaps between your structures every now and then. 
  • Avoid the advanced versions as much as possible such as Advanced mills and etc. Stick to the regular mills/farms until you have more income or you’re out of room. 
  • Build safely! Even if a spot is great, if you don’t have the units/towers required to defend that structure build it elsewhere more safe. 
  • Find a good open space for your housing. Even if that means pushing out with a Tesla tower you’ll have a much greater bonus from market/bank later and is generally worth it.

Short Summary

I think the list above already explains a lot, but as a golden rule, you should keep gaps and space between every now and then. You never know when things might go south.

So it is a good idea to be slightly safer and give you the room for error so you can get some extra walls if needed. I really recommend especially to the newcomers.

Take your time pause the game and plan a bit longer you are given all the time in the world for it!

Also as I mentioned above the farms and other income buildings it’s worth to go for the lower number and get more of them. To my experience you will wil by 20-30 food and
likely with 2-3 stone/iron. The same applies to hunter cottages and fisherman. However make sure you build safe. If you can’t defend it, just for one instead and build it closer to your base or in a safer spot in general.

So that’s it for the buildings thus far.


When it comes to units probably a lot of people may agree or disagree with me. Anyhow here’s a list of things about units that you can take under consideration.

General Unit Strategy Tips:

  • Start with more archers and try to aboid TOO many ballistas, because ballista’s upkeep is pretty high 
  • When pushing out with rangers keep space between them. They make next to no sound and you push out a lot faster like that. 
  • Use soldiers with care as they make a lot of sound and will generally attract too many zombies. 
  • Put soldiers and snipers into towers later to increase their range 
  • Snipers are by far best for clearing map. Roughly around 20+ is enough to clean mostly everything. 
  • Combine your units such as rangers with snipers when clearing. Rangers are fast moving and you’ll be able to use them to kite some situations. 
  • Thanatos are amazing for clearing mid/lategame raids so go crazy on the production of them! 
  • Be careful with lucifers as they can kill your own units. Make sure they are in front of all your other units. 
  • Titans are expensive and should be avoided mostly. They are however “okay” to clear the map with, but again way too expensive.

Short Summary

As you may have noticed I didn’t go over lucifers or titans as much. It is simply because these units don’t have much use case sadly. Lucifers range of fire is very short
and on top of that they are very dagerous to use. What if an harpy jumps into your thanatos and then lucifer FIRES AT WILL.

So what about titans? Don’t get me wrong! They are amazing units, but for the cost of 6000 to research and 2000 to build? You’d be getting a nice pack of 30 snipers for all
that money and way sooner as well! I’d recommend anyone to use executioners for defensive purpose.

Again remember that soldiers are also great for clearing map, but nothing comes even close to snipers. You can also combine all of them to clear, but as from my experience your
archers and soldiers will still get hit by spitters and harpies and take my word, without any management they will soon die.

So if you don’t want to spend too much time managing your units simply use snipers and you can spend your time on buildings/defense instead.


Defense is as much as personal preference as units, but I’m sure some it may become useful to a lot of people.

General Defense Tips and Hints:

  • Walls, walls and walls. Make lots of use out of wood walls at the start as they are very inexpensive. 
  • You can cover the side of your outer buildings with 1-2 walls if you don’t have units yet to defend with. It will give you the time to react and get a unit to kill the zombie hitting the wall 
  • Stay safe and build a wall covering a tunnel area. 
  • Generally look for those “choke” points and cover these with a possible ballista. 
  • Don’t go too heavy on ballistas as their upkeep is 15 gold. That literally equals 15 archers that are also mobile and help you clean faster. 
  • Block off tunnel sections with stone walls and leave some units to defend it. Again don’t build towers unless nessecary. 
  • Use wood/stone towers to give your units better range of fire. 
  • Use shock towers for mid/late game raids. Try to only cover the very outer edge of your wall and build it as back as possible to stay safe from spitters. 
  • Combine your thanatos with executioners, snipers and shock towers for an effective defense. 
  • Create 3-5 layers of wall. You may also throw in some spike or fence traps in-between if you wish.

Short Summary

So this was the defense section. Again I think it’s all up to your personal preference or what you have found to be more “effective”. Honestly the most important unit
in your entire defense is thanatos. They are mobile and they completely destroy the hordes. So your main ephasis should be getting thanatos. It’s fine if your wall
gets destroyed, you can just quickly build an extra wall behind and fall back with thanatos and clear what was left of after the main wave.

You should not go too heavy with towers. having the mobility is a big deal. If you end up in a situation where you had mainly towers only and your defense breaks then you
might not be able to recover from it simply because you don’t have enough fire power to deal with the siatuation.

Anyhow your final mix is up to you, but I recommend you to use the snipers/thanatos/shock tower/stone walls. This is what I’ve found to be most effective. And feel free to throw in
some wood towers for your snipers, it helps out against spitters.

In the video below you’ll also notice a wood tower that I left empty and my snipers didn’t have the “range” to kill them without it.

Helena Stamatina
About Helena Stamatina 2715 Articles
My first game was Naughty Dog’s Crash Bandicoot (PlayStation) back in 1996. And since then gaming has been my main hobby. I turned my passion for gaming into a job by starting my first geek blog in 2009. When I’m not working on the site, I play mostly on my PlayStation. But I also love outdoor activities and especially skiing.

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