Rafał here! I am one of the developers who built this game, happy to answer anything!
Thanks for joining in!
In your opinion, what was the most interesting challenge you got to tackle when building the game?
Undoubtedly, the most interesting challenge was the implementation of the hint system. You wouldn't believe me how complex this problem is! Solitaire is a game that is easy to start, but really hard to master - sometimes to unlock a card you must move cards back and forth from the "foundation" (piles in the upper left corner of the board). It makes lots of combinations, that are really hard for a computer to explore!
That's awesome, great job for cracking it!
Was that a tree search based solution?
No, after a few tries, we decided to use a heuristic algorithm. Basically it's looking through all possible moves and checks which moves are getting us closer to solving the deck.