Surrendering Optimally
There I was, working on the computation puzzle for the 2025 tournament, when I see this show up.
Few things would get Grimmy pinging me out of the blue, and nearly all of them are worth my immediate attention. It was one of those things. The Opus Magnum community had broken another cycle record. This time, it was Surrender Flare.
A Notorious Puzzle
Surrender Flare appears at the end of chapter 2 of the main campaign. It is the first puzzle in the game to require you to use a debonder, as well as only the third puzzle to even provide you an input with more than one atom in it at all. That earliness leads to a sort of legend status.
New players have something of an inherent “bounce rate” as they try any Zachtronics game. Once they reach a puzzle that they don’t enjoy solving, they will “bounce” and put down the game, often forever.
These numbers, provided in 2022 by Zach of Zachtronics, show that 87889 people have solved Surrender Flare. Comparing to the other notorious levels with cycle breakthroughs from last year, that’s nearly twice as many as solved Litharge Separation, and nearly 4x the number who solved Universal Solvent. If we go to my pride and joy Refined Bronze, another graph shows only a paltry 1156 people have solved that one.
With this many eyes on the early game, Surrender Flare is far better known. And then there are the memes..
Surrender Flare Memes
People who get to Surrender Flare don’t all know the mechanics of the game. After all, this is the first puzzle to have the player use a debonder. A common misconception is that you have to debond and rebuild the molecule in its entirety to complete the level. This leads to machines like the following:
This is the earliest I can find on reddit, from the day after the game came out, but I’m sure that many others did the same even before this. Just on sheer numbers.
For the record, the glyph of projection works even if the metal it is promoting is bonded to other atoms. The only reason one needs to break a bond is so that there is a tile to put quicksilver. So, a more economical solution may look like this:
Due to the misconception though, many new players will make an overengineered solution to this puzzle, then head to the internet to share their triumph. Seasoned players regard this as a rite of passage. Unintentional flareposting is the top of the Opus Magnum iceberg. Intentional flareposting is a little bit deeper..
Surrender Your Flares
Peak intentional flareposting has to be Steven’s discord thread called “surrender your flares.” I believe she has solved the puzzle at least 100 times, always with some overengineered monsterpiece. Here are a few examples:
And I would be remiss to leave out Ceres_The_Cat whose intentional flarepost is sitting as the top post on r/opus_magnum of all time.
She makes a point of disassembling the entire flare, only to then bond the central iron to it anyway before using the projector. It is a great and horrible thing. All this to say, this puzzle has brought a lot of collective joy and some agony to many thousands of people.
All without being solved optimally.
Cycle Theory
4 days after the game released, Racher11 posted this:
That’s a lot of machinery, and this time it’s all for a good reason!
The puzzle is solved when your machine makes 6 outputs. Each output uses one flare input and one quicksilver input. If trying to get the lowest possible cycles, grabbing those inputs as quickly as possible is the first step.
Each input needs to be rotated as its first movement, because the input glyph is too large to clear in a one tile slide. Because arms need to spend a cycle grabbing, one arm is too slow to to rotate inputs at maximum speed. At least two arms need to be responsible for moving the inputs, making the machine operate in two halves. This “double pipeline” design is hard to make work. It forces your two halves to reach the same destination from different paths.
Another 17 cycle solution was made a few days later by epnx:
While Racher11’s solution had the arms in the center and the flares flailing around the perimeter, epnx’s solution has the arms around the perimeter, letting the two pipelines proceed through the center. There are still two distinct pipelines, with one projection glyph each.
How does 17 stack up against theory?
Latency
Getting inputs onto the board at the fastest possible rate is the easy part of minimizing cycles. Making the outputs from these inputs is the hard part. Both Racher11 and epnx are taking one cycle longer than strictly necessary, to make outputs from inputs.
To see this, we can investigate the top pipeline of Racher11’s solution in isolation:
This makes its first output on cycle 6, and each subsequent output 4 cycles later. This leads to a 6th output on cycle 6 + 5×4 = 26, the cycle count of this solution. This is perfect latency, but imperfect throughput.
As we trace out the path of the input, we see 3 things happen one after the other. Bond breaks, projection glyph projects, bond reforms. Each of these happens without any time spent idle, bookended by the time on the input glyph and the time on the output glyph. The community calls this an “L=3” pipeline, for 3 steps of latency. For surrender flare specifically, we also call this a “+0” pipeline, since it has 0 unnecessary cycles of latency.
If a solution were to be found that had both perfect throughput and perfect latency, it could make its 6th output on cycle 6 + 5×2 = 16. So why isn’t Racher11’s solution a 16?
Double Pipeline Math
Due to some batching, it is hard to analyze Racher11’s solution further, so I will next turn to my own 17, which has a similar top half to Racher11 but a different and cheaper bottom half. I built this in December 2017, a couple months after release, and it stood as the cheapest known 17 for six years.
The bottom pipeline of this solution is +3, meaning 3 unnecessary cycles of latency. In isolation, that pipeline takes 29 cycles:
Can you see those 3 cycles in the gif? Notice how each station now includes a handoff. The molecule is dropped on the debonder and picked back up by a new arm. Same on the projector, and same on the bonder. Where in the +0 pipeline, a tracked arm moved the molecule seamlessly between them, in this +3 pipeline there are 3 handoffs. One handoff costs one cycle.
So what do you get when you combine a +0 with a +3? Well, it depends which one goes first. The two pipelines are staggered from each other by 2 cycles thanks to alternating input grabs, so whichever one goes second gets a +2. If you run the +0 first, it is effectively a +0 and a +5, leading to outputs on 6, 10, 11, 14, 15, 18. If you run the +3 first, it is effectively a +2 and a +3, leading to outputs on 8, 9, 12, 13, 16, 17. The same steady state gets either a 17 or an 18 depending on how the machine starts up, but the best you can do is 17.
Symmetric Double Pipelines
The new cheapest 17 was built by a Chinese player known only as W:
With the arms on the outside and atoms in the middle, it much more resembles the build by epnx. However, it is completely trackless as well as symmetric. Rather than a +0 and a +3, this solution has two +1 pipelines. You can see both the upper and lower inputs stall for one cycle to be regrabbed over the debonder, before being perfectly routed from there to output.
With +1 on both pipelines, there is no decision of ordering. No matter what, your outputs are 7, 9, 11, 13, 15, 17.
The symmetric design has less overall latency, as +1 and +1 feels better than +0 and +3. There were examples of +0 and +2 but since the outputs would collide with each other on delivery that is not very useful. The holy grail has always been +0 and +1. With this (or the far more unlikely +0 and +0), you could connect the pipelines to make a 16 cycle solution. As the campaign records for Universal Solvent and Litharge Separation reached their theory limits in 2024, there were more inquiries into Surrender Flare 16. Let’s look at what we had.
Attempts at 16
February 2021, rebix made the following solution:
This was the first ever solution to output twice by cycle 8. It did not repeat at the perfect throughput. It couldn’t, because the +0 pipeline relied on passing quicksilver over the hole left by the flare input on the pictured cycle:
This input suppression meant this stood more as a novelty than as a real point of investigation, but it kept coming up as “the only time ever that we found 2 outputs by cycle 8”. A +0 and a +1 pipeline converging on the same output. Just don’t try to run them at throughput.
In 2022, a player known as AXZIOM arrived, whose sole goal in the game was to find Surrender Flare 16.
They began enumerating all +0 pipelines. This led to an extensive collection of first-output-on-cycle-6 solutions. The album can be found here. They hoped that one of them would match with a +1 and 16 would be solved. However, their search method was not exhaustive. It identified 45 different pipelines, which Grimmy now reports is only about 21% of the true total.
In 2023, rebix made his own attempt at enumerating +0 pipelines.
This didn’t result in anything new, further cementing the idea that maybe 16c was not possible.
Shadowcluster made a quiet statement that he too was looking. Many great players all gave it an effort. Still all we had was the one solution by rebix.
Grimmy
Grimmy is a super active player who has been around since day 1. On March 3, 2025, after a few hours of silence, they drop this on the chat.
It eventually came out that they repurposed scripts, originally used in their hunt for Stabilized Water Paretos, to look at merging pipelines on Surrender Flare. This yielded some results, including the second ever known machine to output twice by cycle 8. Unfortunately, it has the same problem, needing to suppress the input using quicksilver in order to make it to the projector:
But then they found one that didn’t:
Quick Follow-Through
This community pounced on this layout, seeing surrender flare 16 as now a very possible future. Certainly there were arms that needed more than 4 cycles to return to their original positions, so it wasn’t already set up for looping. But the atom routes gave no conflict, which is the best we had ever known hope on this puzzle.
The first 16 came together at the hands of rebix, but he even said “this is all grimmy.” The design was in some sense the natural continuation of the gif Grimmy had posted some 40 minutes prior.
That brings us to the ping that opened this blog post:
Immediately afterward, mr_puzzel (Isaac Wass) made his own continuation of Grimmy’s machine, coming in far cheaper:
Analysis
Much like Racher11’s original 17, these machines are very clearly batching. After the 6th output, there is some downtime spent not at perfect throughput. This is because the arm programming isn’t capable of repetition at that rate – arms aren’t where they need to be when they need to be there. There is just enough space to cram in enough arms to handle the first 4 products “well enough”, and then the last 2 products exactly as in Grimmy’s gif.
It is hard then to call this a +1 and a +0. It has the two projection glyphs, but the ways the molecules interact with them vary one to the next. Part of the reason is the central hex arm. It can do two different jobs: take salt from lower debonder to lower bonder, or take flares from lower bonder to output. It does both jobs for the first and third flares on that pipeline, but the second has to be handled differently to avoid a collision over output.
That doesn’t mean that every 16 will behave in this way though. Grimmy has only explored a portion of the 8c@2 solution space. In their words, they have found:
- 213 6c@1 ignoring qs solves (i believe this is exhaustive)
- 27125 7c@1 ignoring qs solves (this is nowhere near exhaustive since i didn’t even implement regrabs yet)
- 2836 8c@2 ignoring qs solves (straightforward merging of the 6c and 7c solves)
- 51 8c@2 full solves
They “didn’t even implement regrabs yet” meaning that their +1 pipeline is always just a +0 pipeline with an extra move for geometry’s sake. It never hands over control of the main flare to another arm during projection or debonding. It is entirely believable that somewhere out there are the well behaved 16s, that look like the well behaved 17s but faster.
Records At Time Of Writing
With continued tinkering, there have been other 8c@2 that look promising, but nobody has closed them out like the first. The cheapest is 420g, a small modification of mr_puzzel’s gif above:
While the smallest is a mere 3 area smaller than the cheapest:
RP0 has taken to trying to sort these by a different secondary though. Among 16 cycle solutions, which has the best lexicographic cycles? That is, which solution outputs the first output quickest, ties broken by second output timing, etc. This metric was featured in the 2023 tournament. It’s strange because 16 cycles already makes the 6th output the most important, so the lexicographic ordering as secondary is more like alphabetizing the English language by 6th letter and then first.
Currently, without accounting for overall cycles, the best lexicographic cycles solution to surrender flare has first output on cycle 6, second on cycle 9, third on cycle 11:
Beating the old lexicographic cycles record which had first output 6 and every output 3 cycles apart (so 9, 12):
Grimmy has ruled out first output 6 second output 8 by exhaustive search: none of the +0 pipelines match onto other +0 pipelines. That means that the best we can hope for is first output 6, second output 9, third output 10. The hunt continues for that.
Alcohol Separation
With Surrender Flare now at 16 cycles, only one puzzle remains not at its theory minimum value. That is Alcohol Separation, the first puzzle from chapter 3. All players who beat Surrender Flare gain access to Alcohol Separation which should make it almost as well known. However, it doesn’t have as many memes. Alcohol Separation is the first puzzle to require the use of Van Berlo’s Wheel, and also has a theory minimum cycle count of 16, and a record of 17.
The first 17 was built in November 2017 by none other than Grimmy:
While the cheapest now known was built originally by W and further improved by Grimmy:
With 4 outputs, there is a little more freedom to spread out, but the machine only counts as done when all 4 of the outputs have seen 6 products deposited. There is a solution which outputs 3 of the 4 outputs fully by cycle 16, but needs one additional cycle for the final earth, made by Villfuk (the same person who took down Litharge Separation 23):
A few people have taken serious stabs at bringing this to minimum. One such player is spectria.limina. A few years ago, she took on the puzzle Creative Accounting, which is notable for having the exact same input shape as this, and brought it to its theory minimum of 22. While it isn’t possible to objectively rank difficulty of cycles barriers across different puzzles, it seems like that success and Alcohol Separation 16 are reasonably close to each other..
If we achieve the 16 here, the community will have completely defeated the main campaign of Opus Magnum. The cycle records will be perfection.
If we hurry, we might even make it before the DLC. Stay tuned!
The hardest cycle to cycle