Once they have been built, certain construction sites (like the Great Pit, for example) can be upgraded. Each day, the citizens can vote for one, and only one upgrade. Citizens should vote for whichever upgrade is more useful for the town.
Just before the 23h00 (server time) attack, the upgrade which has received the most votes is accepted and constructed immediately.
Upgrades are free: they require neither AP nor resources.
Each upgrade can be improved up to 5 times, each level being increasingly powerful. These upgrades can have numerous effects on a town :
- improved defences,
- increased water reserves,
- reduced construction costs,
- detection of zombies,
- special abilities...
Warning: choosing one upgrade over another is very important! Bearing in mind that a town is limited to one upgrade per day, a town which lasts 10 days is only entitled to 10 upgrades, so choose wisely!
Discuss it in the forum!