Every day in the game, all houses are checked:
Whether a house has all required goods and service is determined by the c3_model.txt file.
Houses of level medium insula and below have the ability to merge into a single 2×2 house.
A house will merge with its neighbours when:
When a house evolves, it may need to expand:
|From level||To level||Size|
|Medium insula||Large insula||1×1 to 2×2|
|Medium villa||Large villa||2×2 to 3×3|
|Medium palace||Large palace||3×3 to 4×4|
A house can expand in 3 ways:
A house can expand in 4 directions. Option 1 is tried in all 4 directions, then option 2 in all 4 directions, then option 3 in all 4 direction. If a way is found to expand, the house will expand.