Countries of the World card game published by H.P. Gibson & Sons, Ltd as part of their International Series, c.1939. There are three separate series of cards, covering the various countries around the world. Series No.1 has 12 sets of countries, each set having a map (keycard) and associated information cards listing the main features of that country and which make the complete set. The number of cards in each set varies depending on the importance or size of each country. See the Rules►
Series No. 1: the 12 Maps
Series No. 2: the 12 Maps
Series No. 3: the box and 12 Maps
As far as the yellow coloured contries are concerned they seem to be countries whose sovereignty might have been questioned and indeed later were annexed by other countries. For instance Tibet which always regarded Tibet as theirs after Britain let go of it and was only taken over officially in 1950 (I remember it well when the Dalai Lama had to flee for his life to the UK). Austria was about to be Anshlussed. Poland would become a target for Germany.
The International Series brand continued to be used on some products until early 1980s, competing against other established names such as Chad Valley, Spear’s and Waddington’s.