Show HN: Eyeball (opens in new tab)

A modern take on Matthias Wandel's classic [0], which has you guess a variety of geometric attributes (e.g. angle bisection, centroid locating, shape regularization), not just simple partitioning of a line.

[0] https://woodgears.ca/eyeball/index.html

I was 0.06% off on eyeball. Beat me: https://eyeball.rory.codes.

This is fun!

Definitely need an iOS version! An angle version on a circle would be nice too.

It's interesting that there are, at the time I'm commenting, 11 new users commenting on this submission, some commenting multiple times. I wonder what the effect of "share my score" type pages have on account creation.

This is fun but you need to put "click the line" higher on the page. It took me a while to figure out what I was looking at.

Love it!

It would be great to have a 'training' mode, where you get to repeat ones you miss. This would increase the learning speed.

Easy training- repeat the one you just borked Medium training- cycles through say 5 examples until you get all five within your target range (1%, 0.1%, whatever)

Got a perfect result for the first try. (Off by zero.) Not trying again. :)

https://eyeball.rory.codes/ I was 0.20% off on eyeball. Beat me: https://eyeball.rory.codes

Great idea! Have you considered storing triplets <range, correct number, selected number> for each try and making image plots of these (x/y coordinates are correct/selected numbers, color of each pixel represents frequency) for multiple users for each range? I think the image might reveal interesting properties of human eyeballing, like near-perfect accuracy around 50%, but with less obvious correlations.

I love these kind ones! Really engaging also yes as someone commented, the training mode would be an awesome idea.

Also, I tried this on laptop as well as my phone, I liked it more on my phone (I know the whole point is about precision though)

Note the "share" link doesn't share a specific challenge for others to try, which would be much cooler, instead it just shares to main page

I was 0.67% off on eyeball. Beat me: https://eyeball.rory.codes

I love these simple games that take 2 seconds to understand the rules.

Off by 6 on my iPad by mis-clicking. Very satisfying!

This is fun! and I really love the clean and modern UX.

I am amazed how such a simple app gets that much attention , whereas probably it is vibe coded in an hour using Claude or any other AI tool .

This is very cool and fun. Thank you.

Well I suck.

my best is 0.08%

It's a bit of a cheat, but you can hit 0.00% every time. Just measure the bar length, then cross-multiply. :)

Example: bar is 1250px, max is 2100, number is 376 → (1250 × 376) / 2100 ≈ 223.8px from the start, that's the 0.00%.

The fact that the numbers are in a brighter color than the end marks, and that the numbers go inwards, makes it slightly more difficult than it would otherwise be, because the eye is biased by the more prominent space between the numbers being different from the line between the marks.

0.11% by luck, because I actually got lucky the target number was too close to zero, out of a big scale.

I thought this was a random guessing game and kept randomly clicking and felt very frustrated. Once I realized how it works with the two numbers, estimating felt a lot more rewarding.

I find it very easy if it's near 50%, 10%, or 5%.

Presumably I'd do just as well visually near 90 and 95 as near 10 and 5, the difference is in the first stage, estimating the percentage.

This seems like a nice therapeutic application. Something a person or practitioner could say, “Sit down and play this for 5 minutes to calm your mind.”

Cool idea, love how simple it is. Minimal and clean.

Suggestion: make timed tracks - like a sequence of 10 turns, within max 60/30/15s or something.

Oh, this is actually fun! How about if you change the target every few seconds to add a bit of pressure.

Nice! Would be nice to see your progress over time (if you got better, also as a function of speed...)

I got a perfect "off by 4" on the first try! I feel like I've accomplished something!

I thought I was going to be really good at this but turns out I'm surprisingly bad. Cool idea.

this is fun and helping me get grounded :). adding a timer would be a good idea, I think.

10 round avg 4.5%.

A time limit would make sense imho. For extra challenge, add diagonal or curved lines.

Fun. Got a streak of 4 and one of them was perfect (nearly .10% of target).

My best on first attempt was 0.00% (Pure coincidence) . But was fun!

Its cool man, i was playing for 1 hour, havent won yet

cool game. I tried. would be nice to include a helper description around what to do. took me a while to understand the challenge better.

10 perfect hits in a row!

...

handleClick({clientX: els.bar.getBoundingClientRect().left + els.bar.getBoundingClientRect().width / state.n * state.target })

800

0 out of 1,600

I still missed. Even when there was centered text.

Maybe the human is the weakest link

The low contrast of this website hurts my eyeball

This is wild. Got hooked into it pretty fast

Simple premise, oddly hard to put down.

Really fun! I am pretty much blind

I got 0.03%. I try my best.

very weird comments from very fresh accounts under this post

Would love a time trial mode

Love how simple it is.

I was 0.43% away

really cool! enjoy the simple premise but very satisfying

Super cool stuff!

love it, pulls you in after a first try)

I didn't think I'd be any good at this. What I didn't expect is how wildly inaccurate I'd be on every single goddamn attempt lmao it's like I completely lack whatever part of your brain is required to do this

this is fun!

i got a 0.00% after 3 tries!

Very cool

this was fun

i made 0.87%

pretty fun!

my avg was around 2% not able to do more than that lol