España

Here is a cover from Spain with stamps that feature traditional games from two regions in Spain, Valencia and the Basque country. The stamps the the right shows the game "Pelota Vasca," or "Basque Ball" (funny how it sounds like "basketball"). Since I'm not the best when it comes to explaining the rules of a game, I'll leave it to Correos de España whose website reads:

The Pelota Vasca (Basque ball) is mostly placed in the Basque country, Navarra and La Rioja. The handball variety is extended throughout the country. The game takes place in a court called “frontón” where the players, one or two from each team, stand in the statutory places to serve according to the lots drawn. The player who serves stands some metres behind the start line and runs up to the line, bounces the ball and hits it with his hand towards the wall of the “frontón”. The player from the opposite team hits the ball when it bounces back and this goes on successively until one of the players misses the ball. Depending on the different varieties of the game, the teams scores according to the regulation.

The stamp on the left shows the game "Pelota Valenciana," or "Valencia Ball." Here is a description of that game:

The Pelota Valenciana is a similar game as those played in other countries and Spanish regions and its origins go back to the medieval times. It was played by the nobility and lower classes in the streets or indoors and reached its height during the Renaissance. Later on it was abandoned until the XIX century, when it became a deeply-rooted game of the Valencia region. The Pelota Valenciana is played in the streets and in trinquets (indoor court fields), where two teams of one or a couple of players are opposed face-to-face in different sides of the court and throw each other the ball with their hands until a foul takes place in the opposite field.

From my understanding, the difference between the two games is that the Basque variety is played against the wall and the Valencia variety is played on a court similar to a tennis court (without the net?). The wikipedia article on the game is quite vague, but is seems that the "Pelota" or "Pilota" is a type of ball game (by the way, "pelota" means "ball") that has different varieties from region to region. Perhaps the Basque and Valencia ones are the most popular in Spain or the most representative of all the varities?