Regex Crossword

Posted2 months agoActiveabout 2 months ago

a022311

60 points

22 comments

jimbly.github.ioTechstory

excitedpositive

Debate

20/100

RegexPuzzlesGame DesignProblem-Solving

Key topics

Regex

Puzzles

Game Design

Problem-Solving

The RegEx Crossword is a challenging and engaging puzzle that sparked discussion and sharing of related projects among HN users, with some users praising its design and others suggesting improvements.

Snapshot generated from the HN discussion

Discussion Activity

Active discussion

First comment

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Peak period

Day 5

Avg / period

4.4

Comment distribution22 data points

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Based on 22 loaded comments

Key moments

01Story posted
Oct 28, 2025 at 10:37 AM EDT
2 months ago
Step 01
02First comment
Oct 28, 2025 at 10:37 AM EDT
0s after posting
Step 02
03Peak activity
13 comments in Day 5
Hottest window of the conversation
Step 03
04Latest activity
Nov 13, 2025 at 5:48 PM EST
about 2 months ago
Step 04

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Analyzing up to 500 comments to identify key contributors and discussion patterns

Discussion (22 comments)

Showing 22 comments

a022311Author

2 months ago

2 replies

Yesterday, I discovered regexle [1] and today found out that this was the inspiration for it.

I think I've seen this puzzle before, but I really enjoyed myself gradually solving it while doing other things in the last two hours. I'm sharing this for anyone else who wants a way to spend their afternoon!

[1]: https://regexle.com

hdjrudni

2 months ago

3 replies

I like that one better. Smaller. More manageable. I don't want to spend 2 hours deciphering the big one.

Took 4.5 min to solve #519. Would have been quicker if I started with a better strategy but it was my first time.

GordonS

2 months ago

1 reply

Got 3m 32s on #519!

#520 seems much harder tho!

What a great game, just wish the colours were configurable (colour blind)!

C1arkgable

about 2 months ago

Checkout the high contrast mode in settings, it should be colorblind friendly!

Levitating

2 months ago

I got #520 in 3m 8s with some practice on the big one.

I thought the bigger one was more fun though, I'll continue with that one now.

hughes

2 months ago

519 seems to have at least 3 solutions... feels a little underconstrained!

C1arkgable

about 2 months ago

Thanks for posting about Regexle! My buddy and I made it last year, inspired by Jimbly, but we regularly forget it's still up. Stoked that folks are enjoying it. If you have any suggestions for improvements, we're open to em! https://gitlab.com/Nathaniel.Belles/regexle/-/issues

Levitating

2 months ago

3 replies

It seems impossible?

On the left a horizontal must start with F: F.[AO].[AO].*

However, the diagonal for that cell may not include an F (aside from the start): [^X]*(DN|TE|NI)

glxxyz

2 months ago

1 reply

[^X] means any character other than X, so [^X]* matches zero or more of any characters, so long as none of them are X.

Levitating

2 months ago

Ah my bad! I did misinterpret [^X] as X or the line-start.

throwaway019254

2 months ago

[^X]* means anything but X as many times as you want. So F will match this part.

rzwitserloot

2 months ago

BIG EDIT:

Because it's so trivially unsolvable, I had a quick look at the posted solution.

We're reading it wrong.

Take the first regex on the top row, one you included in your example:

[^X]*(DN|TE|NI)

You're supposed to fill that in from the bottom to the top.

In other words, the first letter goes immediately to the right of [^c]*[^R]*III.* - that square has to be a 'not X'. The hex immediately below it has to be an E, I, or N.

mcpherrinm

2 months ago

1 reply

https://blog.nelhage.com/post/regex-crosswords-z3/ was posted a few days ago here and is an interesting way to solve these

a022311Author

2 months ago

Yeah, that's how I found regexle, which eventually led me to this!

leddt

2 months ago

1 reply

That was pretty hard! It took me a bit over 2 hours. It took me a long time to get started, it felt impossible. But I found a lot of satisfying "ah ah!" moments that kept me going.

Really well done, but now I don't ever want to do one of these again.

aeonfox

2 months ago

1 reply

The worst is when you're an hour in and there's some crucial wrong assumption you've made at some point that's cascaded across the board and you have to start again. Had to come back to it a day later, but very satisfying to complete. I must be a masochist because I want to do another.

g4zj

2 months ago

1 reply

I'm down to just one unmatched expression, but it's going to require undoing many others to fix.

With so many wildcards (`.*`) involved, it feels as though making a few assumptions along the way is unavoidable. If I start over and only make moves I can prove are correct, I don't get very far.

Edit: Solved! :)

aeonfox

2 months ago

> Edit: Solved! :)

padolsey

2 months ago

For something a bit simpler I made redoku a while ago: https://padolsey.github.io/redoku/

mcdeltat

2 months ago

This is a really cool idea! It seems really hard though, I tried for a while and didn't get far. Would be keen to see one that's a little easier, maybe with less * qualifiers and more + or ?

jxf

2 months ago

I tried this for over 20 minutes and made almost zero progress because I thought the expressions also had to be words, like a crossword puzzle. Oops. It might be worth clarifying that somewhere.

heatpump5n

2 months ago

Great puzzles! Didn't have so much fun puzzling for a long time.

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ID: 45733453Type: storyLast synced: 11/20/2025, 11:59:22 AM

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