Games were developed to take into account all kinds of situations. In tight quarters, you might declare that balls hit on the fly out of the infield were out. If it was confined by walls, a ball might only be considered in play if it first hit one of the vertical boundaries.

Perhaps the most common situation was the lack of actual players. If there were not enough guys for a full field, the boundaries could be shifted so that only one side of the field was fair. You might even replace the diamond with a triangle shaped field thereby requiring less bases and fielders. Games with few guys and smaller fields fit more easily into the street environment and might even become the preferred sport for awhile.