I've been working on a world for a game I'm making. The basis of the game is that you have to carefully manage your resources, and to keep moving. I'd like to build a world which fits that. These are the requirements for the world:
- There is some incentive to move at least once a week; more often is fine.
- There are multiple tribes of people in any given geographic area.
- Said tribes are generally untrusting or outright hostile to one another, and it's not uncommon for one to attack another without provocation.
- The level of tech is at or beyond the early computing (very early; I mean vacuum tubes) era, but no FTL (or if there is, something that prevents other planets from interfering with Earth). I don't really care about computers themselves, but the weapons should have at last the same capabilities as the infantry weapons (i.e. rifles, pistols, etc.) of back then.
How could this develop from the present day? Apocalypses of any sort are fine, but the most realistic solution wins -- i.e., the more possible it is, the better. Bonus points if you convince me that it actually will happen.
Thanks in advance for the help.
Addendum: I'm only looking for things that could happen in the real world. Things using magic or psychic powers are super neat, but not what I'm looking for. Sorry to all the fans of Deathworld out there.