don't want to beat this to death but look up puzzle in wordreference.com and one of the french translations is 'casse-tete', in the sense of a 'toy' or 'baffling problem'. Search 'casse-tete' on google and see what sites there are, lots of game type sites.
Sure the french also use the word 'puzzle', they also use 'lunch' for lunch, but it's because they are adopting english words, those aren't french words.
Keyword tracker shows 'casse tete' gets a score of 1191, and 'casse-tete' gets 343. Not huge but something.
Yes, I know you're french. Yes, I admitted the typo thing is a stretch.
Now I'm sure bdjuf is sorry he started this thread...
By the way, scores for 'cassettes' was 6639 and for 'cassette' was 9055, with a good long tail of secondary results like 'cassette tapes' and so on.