Described as "A Game for the Black-Out", so that dates it to the early 1940's.
It is for two players. Each player gets a board with a 5 x 5 grid on it. The first player selects a letter from the 250 provided and announces it. Both players must now write it into one of the 25 squares on their board. Then the next player draws a tile and both players must now fit that into their grid. Once a letter is placed, it cannot be changed.
The object is to score the most points. Points are rewarded with a specific score, which increase as the length of the word increases. A perfect game would be 5 five-letter words across and 5 five-letter words downwards. I suspect, that would have an absolutely zero chance of happening.
Back to the box - it also says "More Entertaining than Crosswords" and "An Ideal Fireside Game".