Tile World File Formats


Tile World makes use of a number of files besides the data files of Chip's Challenge itself. This document collects information on all of these files in one place.

The Configuration File

Configuration files are used to override some of the settings in a data file, or to set values not provided for by the data file format. Configuration files are by convention named with a .dac extension. A configuration file is stored in the level set directory in the place of the data file; the latter then is placed in the data directory.

The configuration file is a simple text file. The first line of a configuration file must have the following form:


where DATAFILE is the filename of the data file. (Arbitrary whitespace is permitted around the equal sign, but there cannot be any whitespace embedded at the beginning of the line.)

After this initial line, the configuration file can contain any of the following lines:

usepasswords = y|n

This line permits password-checking to be enabled/disabled when playing the levels in the set. The default is y.

messages =TEXTFILE

This line allows for the addition of short textual messages to be displayed in between levels during the game. TEXTFILE names a messages file placed in the data directory. See The Messages File for more information about this file.

ruleset = ms|lynx

This line allows the configuration file to override the ruleset setting in the data file. This is mainly useful in the case where one level set is playable under either ruleset (as is the case with the original level set). The author can then provide one data file and two configuration files to make both versions available.

lastlevel = levelnum

This line marks an arbitrary level as being the last level in the set. The game will stop when this level is completed, instead of proceeding to the next level. (Note that if the data file contains any levels beyond this one, they will only be reachable via a password.)

fixlynx = y|n

This line is specifically for use with the original level set. It is not generally useful, and is described here only for completeness. The chips.dat file that MS distributed with their version of "Chip's Challenge" contained a few minor differences from the original level set as appeared on the Lynx. A positive value for this entry instructs the program to undo those changes, so that the original Lynx level set is obtained. (The changes made in the MS version were: an extra level was added; four passwords were garbled; and four or five levels' maps had minor alterations.)

The Messages File

A messages file is a plain text file that contains (usually short) paragraphs of text that are meant to be displayed in between levels. The original game displayed messages after every ten levels (thus they are sometimes referred to as "decade messaegs"). These messages were not stored in the data file, however, so a separate file must be used to define them.

Each message text is a sequence of paragraphs, with paragraphs separated from each other by a blank line. Line breaks within a paragraph are converted to spaces, and when the text is actually displayed to the user, it will be wrapped to fit the display. (To embed an actual line break within a text, end a line with two spaces before the line break.) A given message can contain any number of paragraphs.

Each message text should be preceded by a line of the form


which associates the following paragraphs with that level number. If N is negative, i.e. preceded by a - character, then the message will be displayed before the level, when it is initially visited. Otherwise, when N is positive, the message will be displayed at the successful completion of the level, before proceeding to the next level. (Positive values can be prefixed with a + character, but this is not required.)

Messages can appear in any order in the messages file.

The User Configuration File

Tile World stores a couple of user-controlled configuration values in a text file, to be used as default settings on the next invocation of the program. Each entry in this file is a single line of the form NAME = VALUE and NAME typically matches the name of the equivalent command-line option.

There are currently two possible values in this file:

volume = N

This line sets the initial volume level. N can be any integer between 0 and 10.

initial-levelset = LEVELSET

This line identifies a particular level set to be selected at startup.

The Solution File

Tile World saves its solutions in binary files, typically named with an extension of .tws. Solution files are stored in the save directory. They are the only files that Tile World actually creates.

Note that all numeric values in the solution file are stored little-endian, for the sake of consistency with the data file format.

A solution file begins with the following eight-byte header:

   0-3   the 32-bit signature, always equal to 0x999B3335.
    4    the ruleset of the solutions: 1 for Lynx, 2 for MS.
   5-6   the number of the most recently visited level.
    7    count of bytes in remainder of header (currently always zero).

When reading a solution file, a program should always read byte 7 and seek past that many bytes before continuing. This allows for future expansion of the header.

After the header is a series of records. Prepended to each record is a 32-bit value that indicates the size of the record. Thus, a program does not need to fully examine each record to find the next record.

Two special size values should be noted here. A 32-bit size value of zero ostensibly indicates a zero-length record, and can be safely ignored. A 32-bit size value of 0xFFFFFFFF indicates that no more records appear in the file -- i.e. it functions as an EOF marker. (Neither of these values appear in solution files created by Tile World, but they may be useful to other programs in certain situations.)

The very first record in the file is optional. If present, it provides the name of the associated level set, and takes the following form:

   0-5   all zero bytes; indicates that this record is present.
   6-15  ignored; should be set to zero.
  16...  A zero-terminated string naming the associated level set.

This record should not appear anywhere else in the file. Programs looking for this record should examine the first six bytes of the first record. If any of them are non-zero, then it should be assumed that this record is not present.

The remaining records in the file should each be associated with one of the levels in the level set. The levels typically appear in numerical order, but this is not required.

There are two types of records. The smaller record is distinguished from the larger record because it is always six bytes in size. It provides a level's password but no solution, and its format is as follows:

   0-1   the level number.
   2-5   the level password, stored as four ASCII characters.

Note that, unlike the data file, the password is stored in "clear text".

The larger record type provides both a password and a complete solution. This record type has its own header, with the following format:

   0-1   the level number.
   2-5   the level password, stored as four ASCII characters.
    6    other flags: currently always zero.
    7    initial random slide direction and stepping value.
   8-11  initial random number generator value.
  12-15  the time of the solution, in ticks (20ths of a second).
  16...  the moves of the solution.

Byte 7 combines two separate pieces of information. The three lowest bits contain the solution's initial random slide direction. (See below for the encoding of directions.) This value is only meaningful under the Lynx ruleset; for MS solutions these bits should be zero. The next three bits provide the solution's stepping value. Under the MS ruleset this value can only be zero or four; under the Lynx ruleset it can be any value between zero and seven inclusive. The following C code clarifies how the two values are combined:

value = (steppingdir << 3) | slidedir;

After the header, the remaining bytes of this record specify the solution proper. A solution consists of a sequence of moves. A move is defined by two pieces of information: a direction, and a time. Time is, as always, measured in ticks. A single tick is equal to 1/20th of a game second.

For the first move of a solution, the associated time is the absolute time at which the move occurs. For subsequent moves, the associated time measures the number of ticks, less one, that elapsed between it and the previous move. For example, imagine a solution consisted of the following three moves: 0:N, 3:W, 9:S. This would translate to a move north at tick 0, a move west at tick 4, and a move south at tick 14.

There are three kinds of directions that can appear in a solution. The first kind (and by far the most common) is a simple orthogonal direction, and is encoded as follows:

  = north
  = west
  = south
  = east

The second kind is a diagonal direction, and only appears in solutions under the Lynx ruleset.

  = northwest
  = southwest
  = northeast
  = southeast

The third kind of move is created by using the mouse under the MS ruleset. It is encoded as a value between 16 and 376 inclusive. The value specifies a relative x-y offset, ranging from (-9, -9) to (+9, +9). The coordinates are packed into a single move value by the following calculation:

value = 16 + ((y + 9) * 19) + (x + 9);

In the most general case, then, a move requires 9 bits for the direction value and 23 bits for the time value, or 32 bits total. However, in a typical solution, the vast majority of moves consist of small time and direction values. In order to conserve space, there are four different formats for storing move values. The four formats vary in size from one to five bytes. Each value is stored little-endian, so the least significant byte of each value contains sufficient information to determine the value's format and size. Thus, in order to reconstruct the moves of a solution in detail, a program must read the solution as a stream of bytes, examining each value in turn.

The four formats are defined as follows. The diagrams indicate the bit contents of each.

The first format can be either one byte in size:


Or two bytes:

54321098 76543210

In each of the above diagrams, the bits marked with D contain the direction value, and the bits marked with T contain the time value. The two lowest bits contain either 1 or 2, indicating the format and the size.

This format can be used to encode orthogonal and diagonal moves when the time value is 2047 or less. (The smaller size can be used only if the time value is 7 or less.)

The second format is four bytes in size:

33222222 22221111 11111
10987654 32109876 54321098 76543210

This format provides 23 bits for the time value, allowing for any legal time value. Only two bits are provided for the direction, however, so this format can only be used to encode orthogonal moves. Bits 0, 1, and 4 in the lowest byte identify this format.

The third format packs three moves into one byte:


The bits marked with D, E, and F encode three different directions. These are assigned to three consecutive moves. Each move is given a time value of four ticks (i.e. T = 3). Like the second format, only orthogonal moves can be stored in this format.

The fourth format is the most general. Like the first format, it can vary in size. It can be two, three, four, or five bytes long, depending on how many bits are needed to store the time value. It is shown here in its largest form:

33333333 33222222 22221111 11111
98765432 10987654 32109876 54321098 76543210

The bits marked with N indicate the number of bytes that the value spans. Thus N = 0 indicates two bytes, and N = 3 indicates a five-byte value.

Nine bits are provided for the direction value, making this format the only one that can encode mouse moves. The time value is either 2, 10, 18, or 23 bits in size, depending on the size of the value.

The Resource Configuration File

The resource configuration file serves as an index to the various resources that Tile World needs to access at runtime. It is a plain text file, stored in the resource directory, and is always named rc.

The file contains lines of the form:

resource = filename

where resource is a symbolic resource name, and filename is the name of a file in the resource directory.

The resources can be set differently depending on the ruleset that the program is using. A line in the rc file of the form


indicates that the lines that follow only apply when that ruleset is in effect (where ruleset is either MS or Lynx). Resources that are defined before any such line apply to both rulesets, and are also used as fallbacks if a ruleset-specific resource could not be loaded. Note also that some resources need to have ruleset-independent values, as indicated below.

A line of the form

TileImages = FILENAME

identifies the file that provides the images used to draw the game. These images are stored in a Windows bitmap. See The Tile Bitmap for more information about this file.

A line of the form


identifies the file that provides the program's font. The font is stored as a Windows bitmap. See The Font Bitmap for more information about this file. A ruleset-independent font must be provided in order to display the initial list of level sets.

A line of the form

UnsolvableList = FILENAME

identifies the filename for the database of unsolvable levels. See The Unsolvable Levels Database below for more information about this file. Note that this resource should always be a ruleset-independent entry, as it is loaded during initialization.

Four resources define the colors used in rendering text:

BackgroundColor = RRGGBB
TextColor = RRGGBB
BoldTextColor = RRGGBB
DimTextColor = RRGGBB

The value of RRGGBB is a string of six hexadecimal digits defining the red, green, and blue values of the color (as with the color specification used in HTML or X Windows, but without the preceding octothorpe). Again, font colors should have ruleset-independent definitions in order to display the initial list of level sets.

The remaining resources define the game's sound effects. The sounds are stored as Microsoft RIFF files (so-called wave files). Unlike the tile images, each sound effect is defined as a separate file. The complete list of symbolic resource names is as follows:

Sounds used in both rulesets

Sounds used only under the MS ruleset

Sounds used only under the Lynx ruleset

(Note that the symbolic names for the shared and MS-only sounds match the names in the entpack.ini file used by the Microsoft program.)

The Unsolvable Levels Database

The database of unsolvable levels provides a list of levels that Tile World should identify as unsolvable. It is a plain text file, and is stored in the resource directory, and optionally also in the user's save directory. If the file is present in both places, Tile World will use their union.

The list of unsolvable levels are grouped by level set. Each group is introduced by a line of the form:


where LEVELSET is the name of the level set for the following lines.

Each line defines one unsolvable level. These lines are of the form:


where NUMBER is the level's number, and IDENTIFIER is a short string of characters that identifies the contents of that level. The second colon and COMMENT field are optional. If present, the COMMENT should be a very brief sentence fragment describing why the level is unsolvable. This comment will then be displayed to the user when they visit this level.

Note that a single level can usefully have more than one entry, as long as each one has a different IDENTIFIER. This would indicate that a level designer had released multiple versions of a level which were all unsolvable.

The IDENTIFIER is a twelve-digit hexadecimal value, calculated by hashing the level's representation in the data file and prepending the level's size in bytes.

The Font Bitmap

The font used by the program is defined by a Windows bitmap file, which is found the resource directory.

The bitmap uses three different colors of pixels to define the glyphs of the font. The three pixel colors are used to indicate glyph pixels, halftone pixels, and background pixels. When the glyphs of the font are rendered by the program, the halftone pixels will be displayed in the color that is halfway between the background color and the foreground color. Thus the halftone pixels are useful for doing simple anti-aliasing of the glyphs.

The pixel in the top-left corner must be the color of the glyph pixels. The pixel immediately below this must be the color of the background pixels. Any other pixel colors in the bitmap are taken as halftone pixels. Note that the colors used in the bitmap do not affect the actual colors used in rendering the font.

All glyphs must be of the same height, though the widths may vary freely. The glyphs appear in rows, and are read in reading order: from left-to-right, then top-to-bottom. Each row of glyphs includes an extra line of pixels above it. In addition, there is an extra column of pixels running down the left side of the bitmap. These pixel-wide lines contain markers that locate the separation between individual glyphs.

The left column of pixels will have one glyph-colored pixel per row of glyphs in the bitmap. The height of each pixel in the left column indicates the height of the row of pixels above each row of glyphs. All other pixels in the left column will have the background color.

The glyphs in a given row will be separated from each other by a single column of pixels. This column will be indicated by a glyph-colored pixel directly above it, in the row of pixels. All other pixels in the rows will have the background color. There will also be a glyph-colored pixel immediately after the last glyph in a row. (The net result is that every glyph will have a glyph-colored pixel on either side.) Each row can contain any number of glyphs; anything to the right of the last glyph in a row is ignored.

The glyphs in the bitmap will correspond to the ISO-8859-1 characters 32 through 126 inclusive, followed by an alternate set of ten decimal digits, followed by the characters 160 through 255 inclusive. (It is not possible to define glyphs for the characters 0 through 31 or for the characters 127 through 159.) The alternate decimal digit glyphs should be monospaced versions of the decimal digits; Tile World will use these digits to display numbers in aligned columns.

The Tile Bitmap

The appearance of the game's tiles are defined by one or more Windows bitmap files, which are stored in the resource directory.

There are three different formats that the tile image bitmap can use. (The program automatically determines which one is being used by examining the dimensions of the bitmap.) They are referred to here as the small format, the large format, and the masked format.

The masked format is essentially the same one that is used by the original MS program. In fact, anyone with a copy of the original program and a resource editor can extract the bitmap from the Windows executable and use it with Tile World directly. The tiles are laid out in a 13x16 grid. The first four columns of the bitmap are:

  Empty           Clone Block S Overlay Buffer  Wall SE
  Wall            Clone Block E Thief           Clone Machine
  IC Chip         Force Floor N Socket          Random Force
  Water           Force Floor E Green Button    Water Splash
  Fire            Force Floor W Red Button      Burned Chip
  Hidden Wall (p) Exit          Toggle Wall     Bombed Chip
  Wall N          Blue Door     Toggle Floor    Explosion
  Wall W          Red Door      Brown Button    Disintegrate
  Wall S          Green Door    Blue Button     Empty (unused)
  Wall E          Yellow Door   Teleport        Exited Chip
  Block           Ice Wall SE   Bomb            Extra Exit 1
  Dirt            Ice Wall SW   Bear Trap       Extra Exit 2
  Ice             Ice Wall NW   Hidden Wall (t) Chip Swimming N
  Force Floor S   Ice Wall NE   Gravel          Chip Swimming W
  Clone Block N   Blue Wall (f) Popup Wall      Chip Swimming S
  Clone Block W   Blue Wall (r) Hint Button     Chip Swimming E

(See below for comments regarding the tile names.)

The next three columns contain the following tiles:

  Bug N         Glider N      Paramecium N
  Bug W         Glider W      Paramecium W
  Bug S         Glider S      Paramecium S
  Bug E         Glider E      Paramecium E
  Fireball N    Teeth N       Blue Key
  Fireball W    Teeth W       Red Key
  Fireball S    Teeth S       Green Key
  Fireball E    Teeth E       Yellow Key
  Ball N        Walker N      Water Boots
  Ball W        Walker W      Fire Boots
  Ball S        Walker S      Ice Boots
  Ball E        Walker E      Force Boots
  Tank N        Blob N        Chip N
  Tank W        Blob W        Chip W
  Tank S        Blob S        Chip S
  Tank E        Blob E        Chip E

Each of these tiles are drawn with an empty tile in the background. The next three columns repeat the images of the previous three columns, but with a pure white background instead. The last three columns then have the "masks" for these images. The mask images are monochrome, with black used for the background and white used for the figure. When the program is displaying a creature, a key, or a pair of boots, it uses a tile from columns 4-6 if the item is upon an empty tile. Otherwise, it uses the image from columns 7-9, coupled with the mask from columns 10-12, to combine the image with the proper floor tile image.

The small format is an abbreviated layout of the masked format. The tiles are laid out in a 7x16 grid. The first four columns are the same as with the masked format. The remaining three columns contain the creatures, boots, and keys (again, as with the small format) with a solid background of magenta pixels (RGB=255,0,255). When the bitmap is read by Tile World, all magenta pixels in the last three columns will be made transparent. (Magenta pixels in the first four columns will not be altered.) If you wish to use magenta in any of these tiles (e.g., for the balls), then you will have to use one of the other formats instead.

The large format is the only format that permits inclusion of animated tiles. This format has a less rigid layout. Tiles are arranged in rows instead of columns. The tiles are extracted from the bitmap in reading order -- scanning from left-to-right, top-to-bottom. The rows do not have to have a specific width.

A one-pixel-high horizontal line is above each row of tiles. The pixels in this line indicate the divisions between tiles in the row. There is also a one-pixel-wide vertical line at the left edge of the bitmap, which is used to indicate the placement of the rows.

One color is used throughout the bitmap to indicate transparency. This color can be magenta, or some other color. The program determines which color is used to show transparency by reading the color of the second pixel in the horizontal line above the first row -- pixel (1,0) in x-y coordinates.

The vertical line on the left side of the bitmap has a non-transparent pixel at the position of the horizonal lines above the tiles. All other pixels in the vertical line must be transparent. (The non-transparent pixels can be of different colors.) The horizontal lines have a non-transparent pixel at the rightmost edge of each tile image. (Note that the tile images are separated from each other by a line of pixels vertically, but not horizontally.)

The first tile in the first row is the Empty tile. The Empty tile cannot be animated, nor is it permitted to have any transparent pixels.

The next 49 tiles in the bitmap are the following, in order:

Force Floor N; Force Floor W; Force Floor S; Force Floor E; Random Force; Ice; Ice Wall NW; Ice Wall NE; Ice Wall SW; Ice Wall SE; Gravel; Dirt; Water; Fire; Bomb; Bear Trap; Thief; Hint Button; Blue Button; Green Button; Red Button; Brown Button; Teleport; Wall; Wall N; Wall W; Wall S; Wall E; Wall SE; Blue Wall; Toggle Floor; Toggle Wall; Popup Wall; Clone Machine; Red Door; Blue Door; Yellow Door; Green Door; Socket; Exit; IC Chip; Red Key; Blue Key; Yellow Key; Green Key; Ice Boots; Force Boots; Fire Boots; Water Boots.

(Note that there are no tile images for Hidden Walls. These tiles always use the Empty tile image. Likewise, there is only a single tile used to display a Blue Wall, whether the wall is real or fake.)

The tiles can be broken up across any number of rows, and each row can be of different length.

Any of these tile images can have transparent pixels. Those that do will have their transparent pixels replaced with the corresponding pixels from the Empty tile image. Note that if the bitmap is intended to be used under MS emulation, then the Keys and Boots need to be rendered with transparent backgrounds.

These tiles may also have more than one image supplied for them. Those that do will be animated under Lynx emulation; Tile World will loop through the images in the sequence while the game is playing. (Under MS emulation, only the first image in the sequence will be used.) In this case, the horizontal line above the row will have only one non-transparent pixel, placed at the rightmost edge of the last tile in the sequence. (The tiles of a single animated sequence may NOT be broken up across rows.)

The next 10 tiles following these are:

Extra Exit 1; Extra Exit 2; Burned Chip; Bombed Chip; Exited Chip; Water Splash; Chip Swimming N; Chip Swimming W; Chip Swimming S; Chip Swimming E.

With the exception of "Exited Chip", these tiles are only used during MS emulation. They cannot be animated; each tile can only have a single image. Transparent pixels are permitted, however, and will be handled as before.

After these come the following 12 tiles:

Chip; Pushing Chip; Block; Tank; Ball; Glider; Fireball; Bug; Paramecium; Teeth; Blob; Walker.

These tiles will usually have one of a set number of multiple images. Note that some of the possible layouts require rows that are two tiles high. Any given row in the bitmap is of a fixed height all the way across, however. So any change of height between neighboring tile images requires that a new row be started in the bitmap.

The possible "sub-layouts" of the images of these 12 tiles are:

Finally, the bitmap contains three more tile images:

Water Splash; Explosion; Disintegrate.

The images for these tiles can either be 1x1 or 3x3 in size. There should be exactly twelve images for each. (If there are only six, each image will be displayed for twice as long.)

The following notes clarify the meanings of the names used to identify the tile images.

The ice wall tiles are identified by their open sides. Thus "Ice Wall NW" indicates an ice tile with thin walls on the S and E sides.

The parenthetical parts of tile names distinguish between tiles that are identical in appearance. Thus, "Blue Wall" is suffixed by "(f)" or "(r)" to indicate "fake" or "real" walls.

The "Overlay Buffer" tile is used by the program as a place to build up images made with one or more transparent tiles. Whatever is actually placed here in the bitmap will only be visible if a level containing this tile is displayed before it is ever used by the program. Normally this tile contains a duplicate of the Empty tile image.

The "Exited Chip" tile and the two "Extra Exit" tiles are used by the original MS program to create the ending sequence shown after completing one of the two final levels. The two "Extra Exit" tiles are used with the main "Exit" tile to create an three-frame animated sequence.

The "Empty (Unused)" tile in the first two formats indicates tiles that are not used by the program, and normally appear the same as Empty.

In the original MS program, the tiles marked "Explosion" and "Disintegrate" are actually unused, and contain an Empty tile image. These extra tiles only appear during Lynx emulation. (If your masked format bitmap is only intended to be used under MS emulation, these tiles can be left as Empty.) "Explosion" is displayed when a bomb goes off; "Disintegrate" is displayed when Chip collides with another creature.

The "Water Splash" tile is displayed by the MS game when Chip dies from walking into a water square. The "Burned Chip" tile is displayed by the MS game when Chip dies from walking into a fire square. The "Bombed Chip" tile is not used by the original program unless it is explicitly inserted in a level's map.

Note that the "Water Splash" tile appears twice in the large format. The first occurrence is as a single tile used only for MS emulation, and the second occurrence is an animation sequence used only under Lynx emulation.