Gameconfigs manage limits and memory allocation in game. 
In Vestigia, the higher the ped-limit in a gameconfig, the more dense urban zones and some animal-heavy locations are.
The flip-side to this is that the higher the ped-limit in a game-config, the more chance of instability in more extensive modlists and very certain missions.
The default is a 150-ped-limit gameconfig, higher options are in the Alternate GameConfigs folder.
To replace one for the other, copy the game config in the Alternate folder into the global folder in Vestigia.
