A couple of things.

Games, there are any number of games at walmart that are good, Spot It, Yaghtzee, Uno, SkipBo, Scrabble, Checkers/Chess, and more.
We just picked up a new one for a recent camping trip. Called, “Fish or cut bait”, it was fun for everyone and not overly complex.

Books, I have two libraries, the technical which has all the manuals and the other which contains cookbooks, and everything else. Why two? Because I seldom enjoy reading a technical manual compared to a murder mystery, scifi, or the like. There is no escape in a manual, no stress relief.