|The higher the building, the more squads allowed.|
Buildings in Crossfire are similarly 2D. By default, they are single-storey and can accommodate two squads. This didn't have the right look and feel for my 'Crossfiregrad' cityscape, but putting figures on different floors wasn't practical either literally or theoretically.
But then I hit on the very simple expedient of allowing taller buildings to house more squads. The figures are always physically placed on the readily accessible top floor, but while single-storey structures are allowed only 2 squads, two-storey structures are allowed 3 and so on. In every other respect the buildings function in '2D mode'.
This is very obvious and easy to keep track of, and it gives purpose to having buildings of different heights, with the higher buildings forming natural strongholds.