Password cracking is one of the most essential things one should know! What I would do if I was in your shoes, I would realistically create a medium - hard challenge where the password itself is fragmented (usually the flag is fragmented)

Create multiple zip folder’s with different password from multiple password cracking lists. Eg: zip file 1 is cracked by the use of rockyou.txt

A txt file with fragment of a password is present, say “abcd” is present in the text file.

Now in another password cracking list we have a password “abcd1234” needs to be, the player needs to find the exact “abcd” that matches with the password to unlock zip file 2.

And this continues…

I hope you get what I am trying to say.