+1 on the deck of cards. Also include writing materials for keeping score - that can add interest to a game, and by scoring over several games it can last longer. If you don't have paper you can improvise, eg with counters or chips. Pen and paper has other survival uses, but entertainment is an important one.
My current favourite board game is Backgammon. It's easy to learn but hard to master, and there's an element of luck so that even poor players get the occasional win. Second is probably draughts/checkers. Chess comes last because it's harder to learn and slowly paced. With all of these you can probably improvise a board in the field, but it would be better to have a pre-made board and improvise pieces (again, Chess loses because its pieces are more complex). The board doesn't need to take a lot of space; you can get them printed onto a bandanna, eg at
NomadTravel (that's not a recommendation; I've not tried their product it was just the first I found). A pair of dice are needed for backgammon but they don't take much space.
It's worth learning other games that don't need many resources, eg Liar's Poker. I imagine if you have children you already know how many games for them.
Personally I get much of my entertainment from my smartphone. It has a readable screen and I keep many novels in it. I also have a Sudoku game on it which I play a lot. You can of course get other games. In an emergency I'd have to consider battery life and reliability carefully, but it's something I carry and use daily for non-emergencies.
I'd echo what others have said about keeping occupied with (more or less) useful activities. Doug says he included a fishing kit in his survival kit partly for entertainment.