Adults need to continually stimulate the brain. Some games require skill. Among them are chess, go, and mahjong. These each require a set of pieces, but that is insufficient for success. Strategy books are also important.
In the case of chess, the game is divided into the opening, series of moves, perhaps as many as ten, that determine how the game will evolve, the middle game, and the end game. There are books for each part, and the middle game contains books on tactics and others on strategy.
While we are considering games of skill, bridge, a card game, requires quite a bit of study beforehand, and thought while playing. Here, giving a deck of cards might be inadequate, but a good book might be acceptable.
Be certain to point out that in the absence of challenging opponents a good computer can substitute. In fact, computers can be set to a level of difficult, and as one develops to a higher skill level the computer can be reset to that greater skill level. When I first started playing chess I was advised to play those more skipped than I. Playing a weak opponent can lead to lethargy, playing down to the level of one’s opponent, while playing a skipped opponent helps develop greater skills. I think this should be the same for all skill games.