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Hidden Oxygen

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  1. Oxygen atoms cannot be adjacent to each other, even diagonally
  2. Numbers next to rows and columns tell how many oxygens should be in them
  3. Each carbon atom needs 2 adjacent oxygens

Stuck? Press the hint button, which will explain how to come up with the next move.


  • Click once to change state
  • Click and drag to mark multiple cells as empty
  • Zoom with mouse scroll wheel
  • Pan with right button

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A fine game. Having played through dozens of puzzles and reaching the final difficulty, I can attest to its high replay value. I'm also impressed with the visual presentation.

The one thing I'm not a big fan of is the scoring. It takes me considerably less time to score a given number of points while playing lower difficulties than it does while playing higher ones. But I nonetheless appreciated the delay between unlocking difficulties, as it prevented me from getting in over my head while I was getting acquainted with solving techniques.

I would tweak the scoring, but everything else is very nicely done.

P.S. Including advanced-level hints for the final difficulty would be a help!

meekbits responds:

I'm happy you enjoy the game.
From your comment I read, that the progression (delay between difficulties) was ok in terms of time, but it felt unfair in terms of how much points you were getting for solving bigger levels.
I will add this balancing tip to my to do list.

When it comes to hints for the final difficulty it was a tough choice, because these levels are a bit different than the others. By being different I mean there is still only one possible solution, however there's no algorithm that is able to solve them. It would be possible to give some hints, but there would be spots where the hint would say "sorry, I don't know what to do next". So I decided to treat the last difficulty as "uncharted territory" and let the player prove he/she is better than machine :)

But, I get now that sometimes players prefer to have incomplete hints than none at all.

Needing to unlock higher difficulties kinda kills it. Novice is too easy to be fun, I don't want to have to grind through it

interesting variation of windows sapper, as someone had a computer in earlier years, he knows. It is a pity that you have to collect research points, in the sapper you could choose the difficulty level yourself. 4 **** for a bow to this old game

I was really liking it (4+) until I reloaded my browser and lost all my progress.

It was Chrome, and no, of course it wasn't in incognito mode. I'm not /that/ dumb. ; )

meekbits responds:

What browser do you use?
Was it in incognito mode?

Edit: Thanks for providing the details. Thing is, I tested it on Chrome, Firefox and Edge without being able to reproduce it, but other players also reported this problem. Maybe some day I will find the root cause. For now I can advise a mobile version instead, from Google Play Store (if you use Android).

I get a JavaScript/Unity message (‘Error: XDR encoding failure’) on load when using Firefox.

Probably related to the error, but progress made is not progress kept as refreshing the page reset it to 0 for me. Hopefully you can fix as this is a 5 star game otherwise!

Edit: Maybe it’s just my browser. Definitely resets the score the second the page is refreshed

meekbits responds:

Glad you like the game.
Regarding the error, I get it on my Firefox version as well and unfortunately it's something that Firefox has to fix: https://bugzilla.mozilla.org/show_bug.cgi?id=1678243

That being said, this error should be benign and don't cause state loss.
I understand, you got some points, but then after refreshing you had 0? Though I haven't experienced it, I can say that the state is stored locally (IndexedDB). An inability to save to this location or clearing this data will be responsible for losing game state.

Edit: I see other people also report this, but I'm unable to reproduce it.
Maybe some day I will find the cause. For now I can advise a mobile version instead, from Google Play Store (if you use Android).

Credits & Info

3.25 / 5.00

Nov 26, 2020
3:15 AM EST