There aren't that many variations to this cart other than regional releases. The Radiola variations are extremely rare due to the lack of interest in the subject, the game wasn't that popular, so not many were produced under the daughter company names, however rare they may be it doesn't seem to make them much more valuable.
PLAYINGif you could call it a game that is, I would say more of a maths puzzler, the first game is a mathematician, simple logical maths questions and answers, the second game ECHO, is an onscreen Simon says to repeat the sequence game.
INSTRUCTIONS