Are you having trouble surving the first swarm in They Are Billions? Having trouble staying alive until the second swarm?
I’m going to cover a handful of points in this post; hopefully, boil strategy down to its bare essence.
Your first three tents should go up within a couple hours, and then at hour 8 when your first income hits, build the fourth tent, and use the remaining gold to build a food building (hunter’s hut or fisherman’s) and a sawmill. If you can’t get to wood yet, or if there’s a much better place to put a sawmill a few tiles outside your zone, you might put up a Tesla Tower instead. But you need that sawmill; you’ll need the wood primarily for Tesla Towers, but also for Rangers and the first econ buildings.
You should always be building tents or food. If you’re not currently doing either, you should be planning to expand to the next area where you can get food. You might see a great choke-point and think “hey, I want to expand over there”, but your first two priorities should be clearing land towards food (which means grass, trees, or water) and clearing land on which to build.
Aim to build a quarry before day 4; you’ll need the stone to build the first econ buildings. Chances are you’ll start burning wood like crazy, so you should plan on getting a second sawmill up pretty soon, and at least a third (if not fourth and fifth) before the first swarm hits.
Never leave any gaps undefended. After the first couple days, you should bring your troops in close and set them to either block chokepoints or patrol along the larger open areas around your base. Do not give in to the temptation to ignore an approach to your base in order to go kill some zombies elsewhere.
Any time you hear the “Our Troops are Under Attack” announcement, whack that space bar. Pause the game. Go find out who walked into trouble, and get them out of there. Note that many times you can build a “scratching post” — one single wood wall segment — and zombies will be diverted from chasing your doodz to, instead, scratching on the post. This will give your Ranger time to regain health and kill the infected. (Soldiers generally have enough hitpoints and attack strength to not have to worry about this.) Alternately, you can kite the Infected along, loosing a couple arrows into it and then retreating a bit further.
Eventually, you’ll have extra materials laying about (which you should, if you’re aggressive with food and tents). Your next goal in the early game is getting up a Soldier Center, Warehouse, and Wood Workshop. The order that you do these in is up to you; Soldier Center makes clearing land easier; the Warehouse help you accelerate econ; and building the Workshop first lets you get to Ballista sooner — which can be a useful tactic if you’ve got a VOD near your base. (There are other things you could tech into early as well; feel free to explore on your own, I ain’t the boss of you.)
Know when the Swarm announcement will come. For 100-day games, it’s on day 13. For 80-day games, it’s on day 10. (Days 16 and 20 for 120 and 150-day games.) Leading up to the announcement, you should have a hundred gold and 15 wood saved up. When the announcement comes, move all of your extra troops over to that side of the map. See if you can guess the path the infected will take exactly, which will help if you want to build a tower. Otherwise wait til the arrow appears on your map (ie when the wave hits the edge of the map), try again to identify the chokepoint that they’ll hit. Put up 5 walls, hopefully using a fixed land feature to provide additional defense, and park your troops behind the walls. If you’ve got the cash and the wood, you can put up a Wood Tower, too, but note that this takes about 10 game hours to build and it might not be finished until after the enemy is there. More walls will provide a greater measure of security until you get the experience to be able to guess their pathing more accurately.
… and that’s it. Never stop expanding. Never think you’ve got it made. Keep pushing harder and faster, better and stronger.