Idea for late game stage

[saussr]

Each city has an area C1 (1 ... m, 1 ... n, 1 ... k).

 

Array of zombie spawn points Z (1 ... n). And the T1 trader.

If

               (all the points of spawn of zombies in the city C1 are Z (). Killed = true)

               or

               (Or count CQ of successfully finished quests >= 10)

then

               add a Fast Travel Station to the trader T1 (the name of FTS is given / changed by the player).

 

A station (you can represent a mini train station) teleports the player to another T2 trader station of his choice, if such station is exists. Perhaps it scrolls the time in the game (like driving). Saves real time, makes more sense to play in the later game stages.