Since the author seems interested in the maximum number of moves required to solve the puzzle, a similar puzzle called Subway Shuffle far outdoes Rush Hour. For example, puzzle 100 involves 9 pieces on a 10-spot grid, but requires (as far as is known, maybe the solution isn't optimal?) 589 steps to solve. <a href="https://www.cs.brandeis.edu/~storer/JimPuzzles/ZPAGES/zzzSubwayShuffle.html" rel="nofollow">https://www.cs.brandeis.edu/~storer/JimPuzzles/ZPAGES/zzzSub...</a>
It turns out that Rush Hour becomes much harder if we shrink the cars from size 2x1 to size 1x1, while maintaining their direction to be either horizontal or vertical [1].
While the hardest 6x6 Rush Hour puzzle takes 51 moves, the hardest Unit Rush Hour puzzle takes a whopping 732 moves [2].<p>[1] <a href="https://tromp.github.io/orimaze.html" rel="nofollow">https://tromp.github.io/orimaze.html</a><p>[2] <a href="https://tromp.github.io/rh.ps" rel="nofollow">https://tromp.github.io/rh.ps</a>
Great article, very impressive to solve the entire game, rather than just individual puzzles.<p>PS: Good chance that if you're reading these comments that you will appreciate this video by 2swap, visualising solutions to Rush Hour in 3D: <a href="https://youtu.be/YGLNyHd2w10?si=fGFqzEbmV3utbA0O" rel="nofollow">https://youtu.be/YGLNyHd2w10?si=fGFqzEbmV3utbA0O</a>
A little shameless plug:<p>Ive just released a game built around this project on play store - <a href="https://play.google.com/store/apps/details?id=com.noobgiraffe.unblock">https://play.google.com/store/apps/details?id=com.noobgiraff...</a><p>Has 4x4, 5x5 and 6x6 puzzles. Generating 7x7 puzzles is long process and i think i may have to do it on cloud, but am planning to release them soon.
Fun article.<p>The Rush Hour puzzle is quite fun when viewed as a planning problem. In standard PDDL the model becomes very messy. I like the
extensions proposed in <a href="https://arxiv.org/abs/2412.06312v1" rel="nofollow">https://arxiv.org/abs/2412.06312v1</a> that makes the model intuitive.
I played this a lot as a kid. There are so many "levels" - it's fantastic and addictive - but like in a good way where you're using your brain.
Thanks for the article, perfect timing. Was stuck on a secret Santa gift for the brother in law. Rush hour is perfect!