Every chokepoint on the map needs at least two layers of walls before the final wave arrives; if space permits, it is also wise to prepare a third, recessed layer as a backup.You might not always have time to build it before the attack begins, but you can still put it up while the battle is underway—provided the rest of your defenses hold long enough to buy you those extra minutes.
Don't rush in: explore and assess the map first
As soon as the match starts, pause the game to survey your surroundings. Then, send archers out in all directions to scout for the first groups of zombies and recall the units before they are spotted.Scouting also helps determine if your starting location has sufficient food and resources; on open maps, you often have to defend a far-from-ideal spot simply because the terrain leaves you no other choice.
Executors remain the best late-game defense
You should build Executors wherever possible and pair them with stone walls, while avoiding Shocking Towers; the latter consume vast amounts of energy without dealing enough damage to justify their use in the late game.Spike traps are also more of a luxury than a worthwhile investment, as they consume too many resources without lasting very long.Ballistae remain an excellent choice for the early game, especially since they can be upgraded directly into Executors later on.
Terrain is worth its weight in gold
More territory means more food—and consequently, more houses—so it pays to expand early rather than staying holed up in your starting base.If your archers spot an unclaimed stone deposit, it is best to reserve that site for a Soldier Center; after all, more units mean you can occupy and protect a larger area.
Regarding research, if food supplies are scarce, it is best to focus on farms first (and immediately elect a mayor who offers them); otherwise, prioritize cottages.If you can't beat a mission, don't be ashamed to lower the difficulty
Repeatedly failing to progress in a mission is a clear sign that you should lower the difficulty rather than stubbornly persisting; the game is called *They Are Billions* for a reason, and certain zombie waves are designed to overwhelm even skilled players.It is better to complete the campaign at a more manageable level than to remain stuck on the same map for weeks.
