The Combine is a utopian city originated from a communistic mentality with an neoliberal interpretation. The city is built as a communal society in which everything is shared on the condition that what an individual can share has value for the city, The city protects, nourishes and transports its citizens as long as what they have on offer is advantageous for the inhabitants, so the Combine can continue to function as a utopia.
Whenever the city requires something it embarks towards an area where it can be found. If the food is about to be depleted the city will move towards a source of food. When the stock of potatoes has run out and is in demand, the individual or group growing potatoes, will be sought out and included into the city.
To retain a balanced society and keep life in the Combine optimal and pleasant, the 1-in 1-out policy was constructed. Whenever an individual who could satisfy a desire would be taken into the city, the individual of least value would be abandoned so he can work towards acquiring a commodity to bring into the city when the city would require it.
The Combine is a colossal mobile structure crawling slowly over the lands, resolutely towards the next acquisition for the general good.