I didn’t finish this Friday’s Listener crossword, “Absolutely Pointless” by Waterloo, until Monday — figuring out the last two clues and filling the last two cells in the grid during my midmorning break — despite having had Friday off work. Partly because I also had a lot of other things I wanted to get done on Friday, but partly just because it was a very tough puzzle.

The idea is that answers can be entered into the grid in any of the eight compass directions, not just across and down. What’s more, an answer can change direction one or more times. The answer can start in any direction, but whenever the letters N, NE, E, SE, S, SW, W, or NW occur in the word, corresponding to the points on a compass, those letters are not entered (making the grid “pointless”) and the rest of the word continues in that direction (which is usually but not necessarily a change in direction). For example, MOONWALK might be entered as

or perhaps as

The instructions, I thought, were much too terse, and I guess I should give a spoiler alert here in case you are working on the puzzle, because I’m about to write about what, as a former puzzle editor, I feel the instructions should have covered. No clue answers will be spilled or hinted at, however.

The very brief instructions left me with the first impression that entries were going to snake through the grid, possibly changing direction with every letter even where there wasn’t a compass direction to fix what that direction was. It wasn’t long before I saw that if that were true, the puzzle was unlikely to have a unique solution (not without a lot more clues), so I decided to solve with the tentative assumption that an entry couldn’t change direction except where it contained a compass direction, figuring that if that wasn’t the case I would bump up against an impossibility soon enough. I never hit a contradiction, so that was the right assumption to make, but there are probably any number of alternate “solutions” possible without that assumption, and as far as I can see they would be valid according to a not unreasonable interpretation of the instructions.

It would have been nice, too, if the instructions had mentioned that each entry contains at least one compass direction and may contain more than one, that not every compass direction causes a change in direction (when the entry is already heading in that direction), and that an entry may therefore change direction once, more than once, or not at all. These are less crucial pieces of information, as you eventually figure out in the solving that these things have to be true or no solution is possible. But it would have made the puzzle easier to get a handle on if they’d been spelled out.

Worst of all, the instructions did not mention that a single entry may go through the same letter in the grid more than once. BORNEO, for example, might be entered as

This was the omission that really annoyed me, because I figured the natural assumption would be that reusing the same letter is not OK, and that therefore they’d surely mention it if it was, and as a result I eventually reached a point where it was impossible to enter all the answers I’d gotten so far, and I had to scrap my first grid and start over with a fresh copy. Bah humbug. I like a tough puzzle, but I’m not so hot on making a puzzle tougher by making the solver guess at what its rules are. And this puzzle was tough enough as it was!

Other than the frustratingly uninformative instructions, though, I thought this was a fine puzzle. I’ve read some criticism online of the fact that it doesn’t end with any kind of surprise — no hidden phrase appearing in the completed grid, no quotation by Lewis Carroll being spelled out somewhere, that sort of thing. But I don’t see why every Listener puzzle needs to be like that. This was a good and enjoyable challenge, if a very tough one.