@Lar_q give me new ideas writing his last article
Land Ahoy !
Ariadne's thread is not only a great help for solving Sudoku's, but also for the AI (Artificial Intelligence) by making games !
But why not including in a rpg a quest where you (as gamer) need to solve the puzzle/quest with Ariadne's Thread ? (and certainly a Book in the game tells the story about Ariadne!)
Making such a quest it's imo
very important the player can go a path to try if that path is the solution OR has a "dead end" and if it ends nowhere, the player has the possiblility to "reset"(via talking to NPC again, via pulling a lever again, via ... be creative, more is possible, I'm sure!) that dead end path and start from that point(so via "backtracking") onwards ... WITHOUT TO BE FORCED TO RELOAD a previous savegame !! Otherwise it will be very annoying the player must each time reload because he/she comes to a dead end !
Now I'm thinking about a Maze, a very difficult maze where it's important the player must make notes or (more fun!) the palyer has the possibility to drop something (an apple or a banana, a gem or a goldcoin?) at the start of another intersection of roads/paths/corridors ...
But not only a maze can offer good quests regarding Ariadne's thread.
Thinking of Bellegar his poetic rhymes for example: it's maybe fun to include a big quest wherein the player must find out the correct sollution of the last phrase of one of Bellegar's rhymes via asking NPC's about what they know (and what are clearly "failures" you can cancel (overstrike them)) or via reading in books or reading on a board, a wall, a rock, a tree, etc ... or after almost killing an enemy(or persuade a NPC) on your path he/she leave a message or his/her say finally the truth after all the lies ...
It will even more great if it's possible to make a RANDOM quest solution, so if the player replay the game it's again a NEW logic puzzle to solve

!!
Don't know if this can be ?!?
But not make this kind of quest as a part of the main quest because not all rpg players love solving puzzles ... .
And if the player find the solution reward him/her well ! With an extra area to explore (easter egg like in DD!), a very nice reward or even more than one reward only ONE the player can chooce, regardless his/her "build", but each reward give a satisfying gift for many kind of builds ...
or an extra NPC to trade with (and sells stuff you've never seen before !!) ...
The possiblities are legio, I am sure