Pack of cards and a Kindle Touch.

The Kindle is eInk and the battery lasts for weeks. I also have a mobile phone with music etc, but its battery, while fine for day to day use, wouldn't last long enough to use for entertainment in an emergency.

In a pinch I think I could make a backgammon board and improvise dice. Backgammon is the best board game. (Maybe I should add dice to my BoB; they don't take much room.)
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Quality is addictive.