
Interstellar puzzle based on Graph Theory - maxraz
http://treksit.com/?gratheory
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theophrastus
This puzzle is among the very nice offline set of Simon Tatham's "portable
puzzles", with the name of "Untangle" [1]

[1]
[https://www.chiark.greenend.org.uk/~sgtatham/puzzles/](https://www.chiark.greenend.org.uk/~sgtatham/puzzles/)

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fernly
It annoys me that there is an invisible rectangular border to the play area.
The flowing background colors suggest the play area is the browser window but
not so. I could do with more stretch room.

Also (Chrome on MacOS) if you drag a node to the border and it stops, the node
is now stuck to the mouse and you have to click to drop it.

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jstanley
Cool puzzle, and really slick interface.

My one bit of feedback would be that you should make it get more difficult
more quickly. I lost interest and stopped playing it because it didn't seem to
be getting substantially harder, it was just basically the same thing over and
over again, but the design of the puzzle is good and means it should be easy
to make more difficult levels.

Perhaps you could have a difficulty selector so that the player can advance at
his own pace.

You could also introduce a little twist after a while where some of the points
are fixed in space, and you must rearrange the others around the fixed ones,
instead of being able to move all of them.

You could potentially also make different types of edge (e.g. red edges in
addition to the green edges), and for example a red may cross a green, but not
another red.

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darkmighty
I read a while ago a researcher's website specialized in puzzles. He claimed
(informally) the only really "deep" puzzles that can keep you hooked are based
on NP-hard (or harder) problems. Polynomial-time puzzles according to him just
depend on finding a "trick" after which you can solve most puzzles relatively
quick. Specially O(n) puzzles. Which is the case for this planarity puzzle! I
did enjoy the few ones I did, perhaps I didn't "get" the linear-time algorithm
right away.

NP-hard puzzles otoh, are hopeless for hard instances and general algorithms.
Both the designer has to give it more thought on making instances that are not
worst-case, and you have to rely not on general-case algorithms but an
increasing set of heuristics and intuition to solve. Brute force is completely
hopeless.

The same goes for two-player games. If the game can be solved in polynomial
time, one of the players will find a trick (the polynomial time algorithm
essentially) to always win (or depending on the game always draw).

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panorama
A bit disappointed there was no reward for finishing all 20 puzzles, but that
was neat :). I wish the sandbox were big enough though as I kept hitting the
invisible edges multiple times per round.

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jcranmer
Yeah, the final one in particular I wanted a larger box to give myself more
space to move the nodes in.

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vinchuco
Really missed a chance there to make the final boss the complete graph on 5
vertices.

Pic:
[https://en.m.wikipedia.org/wiki/File:Complete_graph_K5.svg](https://en.m.wikipedia.org/wiki/File:Complete_graph_K5.svg)

Why:
[https://en.m.wikipedia.org/wiki/Kuratowski%27s_theorem](https://en.m.wikipedia.org/wiki/Kuratowski%27s_theorem)

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ianai
I thought this was going to be about astrophysics.

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pmontra
The size of the graphs is just right to untangle them on a 5" smartphone. More
edges an it would be difficult to do it without a zoom

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varren
Reminds me of World of Warcraft The Shortest Distance minigame
[https://www.youtube.com/watch?v=GpsoFp2BcSA&feature=youtu.be...](https://www.youtube.com/watch?v=GpsoFp2BcSA&feature=youtu.be&t=0m00s)

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kburman
And I thought that it would be some kind puzzle for testing how intelligent a
life form is. But to be honest i am not disappointed. Nice game.

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rdlecler1
It'd be nice to feel that you had some kind of score. Maybe take percentile
ranking?

