The maximum possible population depends on several factors: the maximum possible city size, the total area of the city, the limit on the total number of cities in the game, the limit on the distance between cities, and the tile productivity settings.
For the modified version of Civ2Mult, the maximum possible population is easy to calculate.
City size: 127 residents (total, maximum 81280000 population in one city). Map size: 65535 tiles. City size 25 tiles. Number of cities: 626. Limitation on the distance between cities 4 and 3 tiles in different orientations.
Total, the maximum can be reached 50, 8128 billion residents. If there were no limitation on the total number of cities on the map, then in this case, a map of size 65535 would contain 2621.4 cities. Therefore, the entire map filled with cities without overlapping areas would allow reaching a population of 213.06739 billion people. If we eliminate the distance between cities in principle (and this is clearly possible, and manipulations with productivity settings, or for example a trick with filling a food box with caravans would allow maintaining 127 residents in each city), and place cities in each tile, then a map of size 65535 allowed us to obtain a population of 5.3266848e+12.
For the TOTPP version, the calculation will be less accurate. In it, the limitation of cities on the map is conditionally 1024 (but, theoretically unlimited, and as I understand, in reality no one has checked this). The maximum map size is 32767. The area of the city is 21.
1024 cities will give a total population of 83.23072 billion. If you place 32767 cities on the map without a distance between them, this will give a total population of 2.6633018e+12.
