Marsh

## Design and Progression Principles Used in the Marsh

Three general design principles are governing the design of the Marsh: the principle of opposition between man-made elements and natural ones, the principle of opposition between analytical thinking and intimate experience and the principle of having separated elements. The three principles are sometime combined to make a more precise rule, for instance the opposition between man-made and natural elements combines with the separation principle so that man-made elements gets separated by natural ones and reciprocally.

As for progression principles, it is worth noticing that movements are very constrained in the man-controlled part of the Marsh because you have to stay on the path created by the metal platforms. The progression in the marsh is thus influenced by the three aforementioned general design principles:

* **Separation:** There are places you can walk on and places you cannot reach. See also how the different rows of puzzles are separated by doors and moving platforms, forcing you into progressing step by step.

* **Opposition between man-made and natural elements:** In the man-controlled part of the Marsh, you can only progress using man-made elements (platforms, underwater rooms...), never using natural elements (water, rocks). More precisely, you use the former man-made elements to bypass the latter natural obstacles. Note also how the stairway leading to the laser goes through the roots of the dead tree stump that hosts the laser box. But in the nature-controlled part of the Marsh, you are more free to walk.

* **Symbolic vs. intimate knowledge:** The artificial separation between walkable and non-walkable areas is not present in the mind as a symbolic knowledge, but we have an intimate experience of it.

In addition to this direct application of the general design principles, there are three derived principles that govern specifically the progression in the Marsh: a strong analogy between the progression in puzzles and the progression in the environment, a focus on connecting distant or separated elements and a correspondence between color mixing and vertical directions. (There would be much more to say bout colors in the Marsh, but this is better understood in a wider context that includes the Greenhouse.)

Finally, in many aspects, the design of the Marsh is an Easter-egg-like reference to Tetris.

## Puzzle mechanics and how they use the principles

In the marsh, each row of puzzles teaches a specific rule or concept, or a specific way to build a solution. So we can present them in chronological order and geographically.

### Entrance puzzle

**Name of puzzle in game files:** `shapers0`.

**Manifestation of principles:** This puzzle has a red background, because Red is the color associated with the principle of connecting distant or separated things, of which opening a door is a special case.

### Row 1

**Localization:** Right after the entrance door.

**Name of puzzles in game files:** `shapers{1,2,2b,3,4,5}`.

**Tutorial for:** This puzzle set uses one polyomino in each puzzle to teach a basic rule, which is: *“enclose the cell containing the polyomino in an area that has exactly the same shape than the polyomino.”*

**Heuristic learned here:** With the last puzzle you may learn an important consequence of the basic rule: the polyomino can only be placed in the puzzle so that it touches the puzzle's border.

**Manifestation of principles:** Note how the analogy between puzzles and environment complies to the heuristic learned: the platforms in the Marsh all "touch" one of the area's border (no platform is an island).

### Row 2

**Localization:** In the back of Row 1.

**Name of the puzzles in game files:** `shapers_merge_intro{0a,0b}, shapers_merge_step, shapers_merge_intro{2,4,3,5,6}`.

**Tutorial for:** this set of puzzles teaches that the puzzles can contain more than one polyomino, and that a zone can contain multiple polyominoes. So the basic rule should be rephrased: *“in each area that contains polyominoes, there must exist an exact paving of this area with the polyominoes it contains.”*

**Manifestation of principles:** Because only the first puzzle can be solved without putting the two polyominoes in a same area, this Row can be understood as being about union of polyominoes, a concept related to the one of connecting distant or separated elements.

**Heuristic learnt:** In the solution paving, a polyomino does not have to cover the cell that contains its symbol. In some occasions it is necessary to move the polyominoes around slightly to solve the puzzle.

### First moving platform

**Name of the puzzle in game files:** `shapers_bridge_control_sliding`.

**Manifestation of principles:** The first moving platform confirms that in puzzles the areas containing polyominoes represent the platforms on which you walk, and the areas without polyominoes correspond to water. It does so by letting players notice the similarity between the puzzle's content and the surrounding platforms. The motion of the platform is also a realization of the concept of connecting distant/separated areas, which will be important in the next row of puzzles.

**Tutorial for:** It also teaches that for some puzzles this representation works in both directions: the state of the puzzle represents the state of the environment and the two are linked so that changing the puzzle's solution will trigger a synchronization of the environment's state and make the platform move.

### Row 3

**Localization:** In the metal structure upstairs.

**Name of the puzzles in game files:** `shapers_merge_433_{3,2}, shapers_gather{1,2}`.

**Tutorial for:** This set of puzzles with red backgrounds require you to master the idea introduced by Row 2, that areas can contain more than one polyomino and that these polyominoes will not necessarily be used in the same configuration than the cells containing them. However, in the puzzles of Row 3, it is mandatory to have all polyominoes in a same area (or possibly two areas, for the last puzzle of the row), and it is also mandatory to change their relative positions so that a polyomino covers the cell containing a different polyomino.

**Heuristic learned:** Row 3 is thus a tutorial for a new kind of puzzle that exploits the basic polyomino rule in a different way: here, you have to find a way to arrange all the given polyominoes so that they form a connected path going through all the marked cells. So the principle is to move the polyominoes so that they connect distant cells.

**Manifestation of principles:** This heuristic is exactly the principle of connecting distant or separated elements announced by the first moving platform (which connects rows 3 to row 2 where the heuristic is introduced), but here, it is a static implementation of that principle. Completing this row opens a door below, which is also a way to connect distant or separated areas. The idea to arrange the polyominoes so that they make a path is also reflected in the design of the Marsh by the way metal platforms are used to make walkable paths, in accordance with the puzzle/world analogy.

### First shortcut door

**Localization:** in the metal structure upstairs.

**Name of the puzzles in the game files:** `shapers_come_together_{a,b}`.

**Description:** On this door there are two puzzles that also have red backgrounds. They use the same polyominoes in the same corners, and only differ by their grid size (5x5 vs. 4x4). The left one requires you to place the polyominoes in the corners, each polyomino used in an area of is own, as in Row 1. But in the second puzzle you have to use the same strategy than in Row 3: inverse the position of the polyominoes and put them all in a same area.

**Manifestation of principles:** The red background signals a use of the principle of connecting distant or separated elements, which is appropriate for a door. These two puzzles also provide another take on the analogy between puzzles and environment, as they represent the two states of the door: At the beginning (first puzzle) the door is closed, and the two areas on each side of the door are disconnected, as are the areas containing polyominoes in the puzzle. But in the second puzzle, the areas are now fused and the door opens, connecting the two world areas that were previously separated by the door.

**Relation with other areas:** Other door puzzles work in a similar way in the Quarry: the two doors near the dam (first door has an S-shaped black-and-white puzzle with the central black area separated in two by the line, but the second door has a serpent-shaped solution that uses the logic of Row 3); and the two starting puzzles in the sawmill.

### Row 4

**Activating the row:** The row is always active.

**Consequences of completing the row:** Opens the door on its left, providing access to Row 5 and the rotating platform.

**Names of the puzzles in the game files:** `shapers_discon{1…4}`.

**Localization:** between two doors, below Row 3.

**Design:** This row has the same colors than the rows 1 and 2, but it contains puzzles with new polyomino shapes (well actually, we should not call them polyomino anymore because of this). Most of these new shapes could not stand by themselves, as there would be no solution to the puzzle: with the 3x3 square where the central block is missing, it would not be possible to draw the line around the central block. For the two-blocks-in-diagonal shapes in the second puzzle, you would need to pass twice at the same point, which is forbidden in puzzles. Same thing for the variant in the third puzzle of the row. Only the double-2x1 piece in the last puzzle of the row could be drawn alone, although 1) it would make two regions and would thus not be recognized as matching the symbol, and 2) It is not possible to place this two-part polyomino in a way that covers its symbol.

**Heuristic learned:** So, the principle of these puzzles is that we should first try to combine these strange polyominoes with others to make a shape that can be traced in a puzzle. (This is different than the puzzles in the previous row where you would ask yourself where to place the polyominoes in the puzzle: here you first need to consider how to assemble the polyominoes before placing them in the puzzle.) More precisely, a good method is to identify in a polyomino the squares that are missing to make the polyomino's contour drawable in a puzzle, and then find how the other polyominoes in the puzzle can be used to fill these holes. That understanding will be very useful later for the blue-outline polyominoes, which require the use of similar strategies.

**Unanswered question:** A curious thing about this row is that it is between two doors. Doors would not be necessary if the designers' goal was just to force us into doing the rows of puzzles one after another: for that purpose it would be sufficient to connect the rows with wires so that you can only start a row after the previous row has been completed. Another reason to use doors could be to prevent us from seeing what happens next, or to prevent us from reaching a point where we can activate something. Clearly it is not the first case, since they made the structure upstairs (with Row 3), from which we have a nice view on what will come next. The reason might be to prevent us from reaching the other moving platforms, but in that case a single door would have been enough (and that would be useless since we can access these moving platforms by using the first shortcut door). So, why use two doors? Of course, we can invoke the general principle of Separation, but it may not be the only reason. Maybe it's related to how we solve the puzzles in that row, but it is not obvious. The strange piece in the last puzzle of the row, with it's two distant parts, could represent the two doors. As all puzzles in this row somehow require to pack polyominoes *inside* another polyomino, this could be a metaphor for packing puzzles between the two doors. Also, this is the first row of puzzles in the marsh that do not use obstacles (holes) in the grid, but doors are obstacles.

**Relation with other puzzles:** Row 2 can be seen in the background, above this row.

### Row 5

**Activating the row:** The row is always active.

**Consequences of completing the row:** Activates Row 6

**Names of the puzzles in the game files:** `shapers_rotating{0…2}, shapers5_rotating`.

**Localization:** Just after the door unlocked by Row 4.

**Tutorial for:** the polyominoes that can be rotated. Notice that right after this row, there is the second moving platform, which rotates. Also, this row keeps it simple: beside the new rule for rotatable polyominoes, it only uses the game mechanics introduced in rows 1 and 2.

**TODO:** there is actually interesting things to say about how the puzzles teach the rotation mechanic and refer to the tutorial rows. See for instance Twak's video.

### Second moving platform

**Name of the puzzle in the game files:** `shapers_bridge_control`.

**Manifestation of principles:** This platform also confirms the analogy between puzzles and environment. It even generalize it by using different colors than yellow for the squares in the puzzle/on the platforms. It also makes the analogy stronger, since the direction of rotation of the platform is defined by the overall direction of rotation of the line you draw (draw it clockwise and the platform will rotate clockwise). And it also correspond to the direction of rotation of the wire that lights up when you solve the problem (there is a wire for each direction).

The principle of this rotating platform is a variant on the principle “connect distant/separate areas”, but this time it would rather be “choose which distant areas you want to connect”. However, you cannot choose to connect opposite exits (for instance, the black and magenta ones). There is therefore two ways to use the platform: the static one and the dynamic one. In the static one, you establish a path between two distant platforms, and then walk on this path as if the moving platform was static (and so, you enter the platform at one end and leave it at the other end). In the dynamic way to use the platform you stay on the platform while it rotates, until it reaches the exit you are interested in (as for the first moving platform). In that case you can leave the platform by the side you entered it.

### Row 6

**Activating the row:** Complete Row 5.

**Consequences of completing the row:** Empties the two yellow underwater rooms respectively at the blue and magenta exits of the rotating platform.

**Names of the puzzles in the game files:** `shapers_rotating_advanced{1,2,4,3}`.

**Design:** This row is the last one to make use of the rotatable polyominoes. It has an orange background that matches the vegetation behind it, but can also be seen as a mix between the red background of Row 3 and the yellowish green background of rows 1, 2, 4 and 5. The reason is that you have the choice to see these puzzles as following the logic of the puzzles of Row 3 with a red background, or to follow the logic of the other puzzles with yellowish green backgrounds, or mix the two logics. Half of the puzzles use holes in the grid to prevent you from placing the polyominoes in the most obvious position (as in rows 1, 2, and 5), but the other half uses polyominoes with unusual shapes as in Row 4 for that purpose. The consequence is that you can either try to make paths connecting the cells containing polyominoes, as in Row 3, or you can first try to combine the polyominoes before placing them in the grid as in row 4. So in the end, that row is a kind of conclusion, summarizing all the puzzles seen until that point in the marsh. And we have this conclusion because after that we will enter a new part of the area with the underwater rooms and blue-outline polyominoes.

**Relation with other puzzles:** The last puzzle of the row is reminiscent of the puzzle of the second moving platform, by the disposition of the cells containing polyominoes, and by the shape of the bottom one.

### Tetris puzzle

**Name of the puzzle in the game files:** `shapers_fours`.

This is the unique puzzle in the underwater room at the magenta exit of the second moving platform. It is one of many references to the Tetris game in the Marsh: each of the 7 tetrominoes used in Tetris are represented once, and all you have to do to find a solution is to pack the tetrominoes approximately where they are drawn, starting from the bottom ones, as if they were falling and stacking. Like in Tetris. Also note that this puzzle is the only one in an underwater room to use the same colors than Row 1, and not to use blue-outline polyominoes. This whole section of the marsh (including this underwater room) is actually optional to unlock the laser, so this is a good place to hide an Easter Egg puzzle.

### Row 7, blue and yellow

**Names of the puzzles in the game file:** `shapers_negative_intro{1…5}`.

**Manifestation of principles:** You enter this first underwater room in the blue water pool, following the principle that the downward direction correspond to subtractive mixing of colors. From the windows in this room you see yellow water, which highlights the contrast between blue and yellow. And in this room, Row 7 teaches the rule for the blue-outline polyominoes. That rule is compatible with the analogy between the puzzles and the environment: Notice how the blocks in the blue polyominoes have been emptied, letting only a blue outline. In a same way, the blue water that filled the underwater rooms has been pumped out, leaving the blue water around the stairway... The areas containing cells with polyominoes thus represent the platforms above water, on which you can walk; the empty areas represent the water. Now, the yellow polyominoes represent all floors on which you can walk, whether they are above water or in an underwater room. And the blue-outline polyominoes represent the underwater floors (which we had never meet before entering an underwater room). If yellow represents anywhere you can walk and blue represents underwater parts where you can walk, the difference between the two is where you can walk above the surface of water, so the rule is that we have to remove the blue-outline polyominoes from the shape containing the polyominoes.

### Row 8, cyan underwater room

    **Names of the puzzles in the game files:** `shapers_negative_overlap_0{a,b}, shapers_negative_overlap, shapers_split, shapers_dither_pattern`.

**Tutorial for:** Row 8 teaches that two yellow monominoes can be superposed if one is canceled by a blue-outline monomino. It allows to ennounce a more precise rule for blue-outline polyominoes: *“Filled yellow is +1, outline blue is -1. Superposing polyominoes adds their values. For each region defined by the drawn line in a puzzle, when the region contains polyomino symbols, there must exist a way to place these polyominoes in the grid so that the sum be exactly 1 in each cell of this region, and 0 in the cells covered by these polyominoes but outside this region.”* (In each puzzle of Row 8, there is indeed at least one cell that must be covered by 2 filled-yellow polyominoes and 1 blue-outline polyomino.)

**Manifestation of principles:** This new rule also gives a more precise interpretation of the correspondence between color mixing and vertical direction, since blue-outlined blocks correspond to going down one level, and filled-yellow blocks correspond to going up one level.

This row also brings a new view on the concept of separation and to the related principle of connecting distant or separated elements (as could be inferred by the presence of some red elements: red-ish canisters in the room and red cube in water). Indeed, what we have to do in the puzzles of Row 8 is to join yellow-filled polyominoes in a same region of the puzzle (similarly to what we do in Row 3) or to combine them together as in Row 4. But each time, this can only be accomplished by first removing a monomino at the intersection of two (or more) yellow-filled polyominoes, using a blue-outline polyomino (third puzzle is an exception as it does not necessarily have to be solved that what, although it is clearly how it is supposed to be solved). So here, combining/joining elements first requires to remove some element. And this view will be important in Row 9.

### Row 9, red underwater room

**Names of the puzzles in the game files:** `shapers_negative_complement_pieces{1…4}`.

**Tutorial for:** This row teaches another rule made possible by the blue-outline polyominoes: *“if all the filled-yellow polyominoes in an area have been cancelled by blue-outline polyominoes, then it is as if the area did not contain any polyomino, and its shape is free.”* Note that this rule is an exception to the rule introduced by Row 8, which would have forbidden that all filled-yellow polyominoes get cancelled (because all the polyominoes that are used in the sum must be in the resulting area... but if you cancel all the filled-yellow polyominoes, then the area does not contain any cell and thus cannot contain the polyominoes).

**Manifestation of principles:** This new rule is compatible with the analogy between puzzles and walkable areas: An area where all filled-yellow polyominoes had been cancelled by blue-outline polyominoes would represent a walkable area that is completely underwater. But in this case you would not see anything from the surface, and you can as well consider that there is no such underwater area. It also strengthen the interpretation of this analogy as a transfer between experience and symbolic knowledge (since knowing that you would not see an area completely underwater from the surface relies on intimate knowledge).

And it may be the right place to notice a nice detail: in this row of puzzles, when you draw the line, its color is light blue. In all other previous puzzles in the marsh, that color was light yellow. Once again, we can interpret that by saying that blue represents underwater or -1 level. Indeed, it is the first time that we have puzzles that represent spaces that are totally underwater. The frontier of that space is not anymore at the surface level (where the line would be yellow), but below the surface, and the line is therefore blue according to the analogy “blue = -1 level.”

In addition, the new rule relates to the last Tetris game mechanic: when a line of blocks is complete, it is removed and all the blocks above it move one line downward. Here, the completion of a line corresponds to when all filled-yellow polyominoes have been cancelled. The removal of the line corresponds to the cancellation of the constraint on the area shape. And the downward movement of the blocks above the completed line clearly corresponds to the rule “outline-blue = -1 level.”

One of the benefits of the new rule introduced by Row 9 is that it allows to put in a same area polyominoes that are too far away and could not be put in a same area otherwise. It is therefore used to satisfy the principle of connecting distant elements. And this concept was previously associated to the red backgrounds. There is no puzzle with red background in this row, but you can notice that we are in the red water pool, which is exactly the same red than the red used for the puzzle backgrounds. Additionally, this underwater room is actually a tunnel allowing to reach the red structure that would be unreachable otherwise. So once again, there is a construct that allows to connect two areas that would otherwise be distant and separated. So it seems that the red color generally represents the concept of connecting distant/separated things, not only the red background.

### Red structure

**Name of the puzzles in the game files:** `shaper_hole_travel`.

**Manifestation of principles:** So, once again, we have puzzles that synchronize their state with the state of the environment, like with the moving platforms. And once again, we have yellow squares on the floor. However, this time, the platforms are not moving horizontally, but vertically. And the puzzles controlling this vertical movement use blue-outline polyominoes in a way that totally confirms the rule “blue-outline = -1 level.” The yellow polyomino represents the platforms upstairs, on which we can walk. The area containing no polyomino represents the water level, on which we would normally not be able to walk. But the red background in the puzzles controlling these platforms is not here only to look like the red water behind it, it also represents the concept of connecting distant/separated areas. And indeed, we use the platforms in this structure so that we can go through it and reach the platform leading to the laser, bypassing the interdiction to walk on water.

Note that the puzzles controlling the platforms of the red structure have a red background (connecting distant areas), the gray grid of movable platforms and underwater room puzzles (the colors of these grids has probably been chosen because it goes better with the blue elements in these puzzles than the yellowish green grids), and **yellow lines**. And there is only another one puzzle with that choice of colors: the one that controls the first moving platform from the cyan pool underwater room. The most interesting color, here, is the choice of the yellow for the line, since all other moving platform puzzles use white lines (and white wires). So why use the yellow here? A better question might be “Why use white lines for the other puzzles controlling moving platforms?” And there is actually an explanation: The line represents the frontier between where you can walk and were you cannot. But you use the moving platforms with white lines for that purpose: to cross this frontier. The white color then represents a frontier that you cannot cross when the platform is still, but that you can cross by being on the platform while it moves and crosses that frontier for you. The puzzles for the red structure and the one in the cyan underwater room use yellow lines rather than white because in the first case, the platforms move vertically and thus do not cross the frontier; and in the second case because you are not on the platform when you activate it from the underwater room. There is thus no need for a white line in these puzzles.

### Second shortcut door near laser

**Names of the puzzles in the game files:** `contemplation_{plus,minus}`.

There are also two puzzles on that shortcut door. Once again these two puzzles represent the two possible states of the door: closed (first puzzle) or opened (second puzzle). In the first puzzle, the yellow polyomino representing walkable platforms are on the exit side and therefore the endpoint of the puzzle would not be reachable from the start circle, since there is an empty area in-between that represents non-walkable water. In the second puzzle, both start point and end point are in the area of the yellow polyomino, and the area can therefore been crossed by walking. This interpretation is coherent with the analogy between the puzzles and the environment and is also a realization of the principle of connecting separated areas.

Symbolically, these two puzzles represent the surface and the underwater rooms: the left one is representative of the simple problems in the first set of puzzles, although using rotatable polyominoes. The right puzzle is representative of the simple problems in the puzzles of the first underwater room, although also using rotatable polyominoes. Together they represent the whole marsh, above and below water, and logically fit puzzles that allow you to exit the area after having completed it fully.

Note that the two puzzles, despite being very similar, cannot have the same solution since the L-shape in the first puzzle must include the top-right corner, but in the second puzzle the L-shape must exclude this corner.

## Environmental Puzzles

### First Moving Platform

The three environmental puzzles that use the first moving platform relates to the concept of connecting distant elements. For one of them, you use the shadow of a disc as a starting point but you cannot reach the endpoint because there is an obstacle (the shadow of some tree). So, you use the motion of the platform to make the endpoint pass on the other side of the obstacle (as you use the platform to pass the obstacle that is the water). For another EP, you have the shadows of two distant half circles (one on the moving platform, one on a stationary pole). So you use the motion of the platform to make these two distant shadows connect (and also to make the endpoint pass on the other side of the obstacle). The last EP (in the cyan underwater room) requires you to make the platform move so that the color seen through the glass circle matches the color of the line/pipe. Here, the separation of the circle and the line is not due to distance, but to color. But we still use the moving platform to make the obstacle of color difference disappear. Note also that the environmental puzzle in the underwater room relies on color subtraction and on removing the color difference, while the two environmental puzzles at surface level require to combine the shadows of two half-circles to make a full circle, so once again we find the idea that underwater is concerned with subtraction, while surface level is concerned with addition, in accordance with the principle of correspondence between color mixing and vertical directions.

### Second Moving Platform

The two environmental puzzles that use the second moving platform are variations on the theme introduced by the first moving platform: you have to use the shadow of a disc on the platform's railing. However, the endpoint is not visible when the start disc is visible, so you have to make the platform rotate. One of the EPs only requires you to rotate the platform so that the shadow of the end of the railing that holds the disc gets visible. It corresponds to the “static” use of this movable platform: you enter on one end of the railing/platform and leave it at the other end. The other EP requires you to end the drawing on the second railing. To do so, you need an intermediate step, going in the shadow of a bar attached to a static pole. And during the rotation, the shadow of that bar seems to move from one railing shadow to the other railing shadow, in a way that reminds how the first moving platform allows you to cross the water, sailing from one metal platform to the other. This second EP therefore corresponds to the “dynamic” use of the platform.

### Third Moving Platform

There are 4 EPs on the third moving platform: one using the structure on the side of the platform (on the boathouse side), and three using the violet stuff at the bottom of the water. The first one using the structure on the side of the platform is a mix of various techniques already used on the other platforms: it contains a starting circle that will only appear as a circle when viewed from the right direction (as the shadow of the disc on the second moving platform only appears as a circle when the platform is at the right position), in addition of being made of two half discs (like one EP on the first moving platform) with different colors due to lightning, that will blend together when the platform is at the right position (as for the EP in the cyan underwater room). For the EPs with the violet stuff at the bottom of the pool, two of them only require to have the platform in one of the two “open” positions, but the third one requires to have both sides opened, which can only be done when the platform is moving. All three environmental puzzles require to remove the obstacle that is the platform, and this is quite unique, because these EPs are traced in natural elements and the man-made platform gets in the way. But all other EPs in the marsh only used man-made elements and when natural elements were involved they were obstacles. We see in that fact another application of the Separation principle together with the opposition between man-made elements and natural ones.

### Other Environmental Puzzles

There is one EP in the boat house and two other EPs involving colored pipes in the underwater room with the Tetris Puzzle, but they do not seem to rely on principles that are specific to the marsh, except maybe for the orientation of the boat (similar to putting the moving platform in the right position) and finding the position where the pipe color matches the color of water seen through the glass circle (as in the EP in the cyan underwater room but without moving any platform).

## Perspective Tricks

There are 3 perspective tricks in the Marsh. The alligator may just be a reference to the Psalm46 video where it is said that "alligator" is a word created by Shakespeare (it's not even sure we can talk about a perspective trick here, since most people do not realize it is actually a log).

But the two other perspective tricks can be seen as illustrations of connecting distant/separated things. It is particularly obvious for the two statues joining hands, which also illustrates the principle of Row 3 where we have to change the relative positions of the polyominoes so that they can connect (the vertical position of the two statues gets inverted so that they can join hands), and also the downward/upward movements present in many aspects of the marsh (e.g. in the red structure). For the dove in the branches it is less striking, although we could say that the figure appears when the branches of three distant trees get to touch each other visually (connecting distant things), that the dove seem to be landing or taking flight (upward/downward movements) and that it is represented by an outline, which is the frontier between what is the dove and what is not, as the puzzle lines represent the frontier between where you can walk and where you cannot — the two being instantiations of the separation principle.

Finally, these two perspective tricks follow the principle of opposition of man-made and natural elements: the dove, being an animal, belongs to the natural realism, and appears in the branches of trees in the nature-controlled part of the marsh. On the other hand, the statues joining hands represent people, have been carved by humans, one of them stand on a man-made metal structure and is in the man-controlled part of the marsh.

## How the Marsh is used

The Feynman and Eddington quotes encourage us to consider the experience of people actually working in the Marsh, which certainly differs from our own experience as a player trying to understand how to progress in the area.

To do...