Found this ad in a pulp magazine Clues - A Magazine of Detective Stories from November 10 1930. The advertiser pleads:

Help! Who can get me out?  I'll pay $8000. Come to my rescue – quick. I'm HOPELESSLY lost in these treacherous, trackless catacombs.

I've tried for hours  to find the right path to freedom but here I am right back in the middle again. Can you find the right path? Will you try? 1000 thanks! – I knew you would. But first let me warn you there is only one path to freedom and it's oh so hard to find... Mark it plainly with pen or pencil and send it to me fast. If correct, I'll see that you are qualified at once for an opportunity to win as much as $2320 cash out of the $8000 in rewards that I'm going to give away. It's all free...

Is this an eccentric millionaire, or a wily entrepreneur garnering the addresses of mug punters, or a publicity stunt?

The clue is the word 'qualified'. Surely this is a forerunner of the Nigerian scams? The maze is probably not that difficult-- you send in your solution and soon hear that you have qualified to win a big prize and must send in, say, $10 (a useful sum in 1930) to enter for the big prize. After that you never hear from him again or are asked for further sums for even bigger prizes. Chap was based in Chicago.