Some guiding tips on how to unlock this achievement for the Siege Survival prologue.
This achievement can be completed during the first of the two battles. You need to reach a score of 38 to unlock it. I chose to do this achievement last, and dedicated an entire save file to it, so I would not have to worry about the other elements, such as food or water. Here’s how I did it:
1. During the first night collect the arrows and then choose to take the axe from the woman.
2. Night 2: As the newly unlocked Bertram, take all your non-essential items (medicine, chicken food), find the shovel and clear the way to the area with the merchant (East). Barter with the trader for some metal and some planks. While in this area, search around for the broken axe; you may also need more wood for the buildings. Head home.
3. The first battle occurs during night three. With the first axe, the first arrows, and two boulders from the trebuchet, you will only achieve a score of 37, so you need to quickly repair the axe. To do this, you will need to quickly create 1 X tools, several planks, build the repair station, then repair the axe. While this is happening, you will also need to collect two boulders that will fall from the sky. Before the battle ends, quickly deposit the following at the Bastion:
. 2 X axes
. The arrows found during the first night.
. 2 X boulders.
This should give you a score of 38, which is the highest possible in the prologue build of the game, and unlock the Strength in Numbers achievement.
It’s worth noting that this took me a few attempts, simply because sometimes the boulders miss, or smash into pieces. Remember that you need 2, so if any less fall successfully, reload the save. You will begin at the beginning of Day 3.
Personally, I never saw any more than 2 boulders drop. If 3 WERE to drop, then you could bypass repairing the axe entirely.
Some hints for day three:
1. the battle won’t begin immediately, so use this time to get as much done as possible.
2. there will be moments when one of your two characters will be idle, try and use this time wisely. While one man is finishing repairing the axe, send the other to stand close to the Bastion (the shield icon) ready to deliver the items.