SOKOBAN

@anian wow, that was very quick testing on your side! I updated my lists with your information (except -4768). I don't know what XSB is but presumably it exports the "black holes" of the levels on this site to empty spaces on which one can move, and that makes levels 2422 2591 2629 2915 2986 3125 3162 3165 3213 4953 solvable

@Mr.Kem the arrows don't work on my browser, which is exactly how I found the S shaped levels; I have to type the URL every time. At some point I asked myself the exact same question anian did, so made a list of levels with no solutions which I manually wrote down. Then I checked which ones are clearly impossible and wrote them down in a separate list. With time I lost some vigour so I don't update these lists regularly, so I missed 4981. I didn't put 916 917 918 4136 in the impossible list because, whilst I believe them to be impossible, I couldn't mathematically convince myself without doubt that this is the case. My lists also ignore anonymous solutions, which is why I missed 4768

@wedge I forgot to mention that -832 also appears twice. I just went thru the rest of the list. They are all unsolvable. Most of them are malformed levels. I also found some of them a bit strange. What I mean by strange is: they are not solvable using the site's GUI to play them. However, if I click on the question mark and then copy the XSB data, they are solvable levels. I think the site admin should either fix the level so it works just like the XSB data, or fix the XSB so that they match with what the GUI displays. These level are solvable if you copy the XSB data and play them using any Sokoban player that can read XSB (but they are not solvable on this site): 2422 2591 2629 2915 2986 3125 3162 3165 3213 4953.

@wedge I went thru your earlier list. For the 8 levels in the collection that has no solution submissions yet, they are solvable. Namely these: 46617 46630 47372 47400 47413 47415 47418 47425. I know because I have a solution. There are two levels someone already submitted a solution: 4768 4981 (user levels). These user levels are also solvable: 3017 4351 4378 4452 4735 4742 4745 4776 4790 4937 4965 4978. These four user levels are known unsolvable: 916 917 918 4136. These two levels no longer exist because the author requested removal (due to unsolvable): 4738 4824. The rest of the listing, I will take time to go over them.

@wedge Thanks for the extensive list! I will go over them when I get time. I just want to point out that for the list you provided, -512 and -1916 appears twice. I basically copied the your list and sort them and found the dups.

@Mr.Kem Thanks for clarifying the Tunnel 61 level!

@anian: there are two versions of Tunnel 61 - the invalid one that you mentioned (lid=2026), which is only accessible by typing or editing the URL, and the official, playable one (lid=2027). Both have the same level number (222). There are quite a lot of these invalid, unsolvable “S” shaped levels hidden throughout the site. If my memory is correct, I think wedge previously provided a list of at least some (possibly all) of these in a Guestbook post a long time ago. During normal play (i.e. using the forward and back arrows to move from level to level) these invalid levels do not appear, so will not affect anyone’s usage of the site.

@wedge Thank you for the extensive list! I will check them out. I am surprised to find that http://game-sokoban.com/index.php?mode=level&lid=2026 (supposely Tunnel 61) is unsolvable. The level looks invalid when compare to other sites on what Tunnel 61 looks like. I think the site admin should at least fix this level to make it right.

@wedge: wow, incredible detective work there! Have you been compiling this list for some time, or did you just do it within the last few hours? Whichever it was, I'm mightily impressed!

I think the best way is to force users to submit a solutions to their levels to avoid further impossibilities