Did you play educational games as a child? Perhaps it was a Teddy Ruxpin, to teach you to read (I had the whole set of characters and books). Maybe it was Where in the World is Carmen Sandiego, or monopoly, or scrabble, or perhaps you played Mad Libs or filled in some educational coloring/activity books.
Japan has plenty of non-educational games for kids and adults (see: Nintendo, for instance) but its history is full of activities designed to teach basics of reading and math. Menko cards aren't just an older, more colorful form of baseball cards in this country - they come with numbers, symbols, and characters to play games - the numbers and symbols can be used for math-based contests.
A common children's game here is shiritori. The basic rules are this: think of a word that starts with the same kana character that finished the previous word. An American version would go like this:
baseball --> laptop --> page --> jerk --> cane --> name --> matchstick --> cream.
In Japanese, the words might be:
yakitori --> rinkai --> itsu --> Tsukuba ---> baka --> kaishain.
Kaishain (employee) ends with an "n" sound, which has its own character (ん) that never begins a word. As such, the person who said kaishain would be the loser. Usually the game doesn't use places (Tsukuba is a city) and only uses nouns, but it depends on the rules. The Japanese version can be much more difficult because of the requirement of a full kana, which means a full
Anyway, adding in some cards, I guess the person has to match the symbol or the color (similar to Uno?), which is why you'll see a lot of the same symbols in the circles below. That is, if you look at the kana.
I picked up this card game (in deck form) at a flea market for 50 yen. I'll change the kana to romanji for you so I can practice my kana reading. Enjoy the cards. The kana characters are kind of stylized and I had some difficulty identifying some of the similar characters - when I figured it out later I might have missed correcting it, and my translations are probably not perfect either. From this point on there's nothing but card images and Japanese practice.