By where you are
No infrastructure to fail, because there was none to begin with.
10 scenarios
Keep moving south. Do not explain why.
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Water is currency. So is petrol. So are you.
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Everyone left. The maths did not.
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One of you is not.
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Above eight thousand metres you are dying either way.
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Nobody knows where you are. You did not tell them.
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You are in their territory. They have noticed.
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The debris comes back around every ninety minutes.
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Water discipline, or you will not last the crossing.
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Nothing in here obeys anything.
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