1

The city has been recolonized by dangerous things

2

The city 's defense grid is capriciously functional

3

Some group maintains the city as a taboo zone

4

The city is full of a lethal toxin or radiation

5

The city's plunder is somehow dangerous to use

6

Some power waits to rob those who come out

7

Broken medical nanites animate corpses to attack others

8

Travel through the city streets is extremely dangerous