Word Rescue Level Format
Word Rescue stores its levels in files named WRx.Sy where x is the episode (1-3) and y is the level (starting at 0). WR1.S0 is episode 1 level 1, WR3.S11 is episode 3 level 12. A matching equivalent WRx.Dy exists but its purpose is unknown - the game will run unchanged if all the WRx.Dy files are removed!
The format is comprised of two layers and some items (perhaps considered a third layer) with the first (background) layer having 16×16 tiles and the second (attribute) layer having 8×8 tiles. Some of the items use 8×8 coordinates while most use 16×16 coordinates.
Each file begins with a header.
|UINT16LE||mapWidth||Width of map, in 16×16 tiles|
|UINT16LE||mapHeight||Height of map, in 16×16 tiles|
|UINT16LE||bgColour||Background colour (EGA 0-15)|
|UINT16LE||tileset||Number in tileset filename (e.g. 0x03 == back3.wr)|
|UINT16LE||backdrop||Number in backdrop filename (e.g. 0x04 == drop4.wr)|
|WR_COORD8||end||Level exit door location|
|UINT16LE||gruzzleCount||Number of gruzzles in level|
|WR_COORD8||gruzzles[gruzzleCount]||Gruzzle coordinates (see below)|
|UINT16LE||dripCount||Number of slime drips|
|DRIP_COORD||drips[dripCount]||Origin and speed of each slime drip|
|UINT16LE||slimeCount||Number of slime buckets in level|
|WR_COORD16||slimeBuckets[slimeCount]||Slime bucket coordinates|
|UINT16LE||bookCount||Number of books in level|
|WR_COORD16||letters||Coordinates of letters in word to spell|
|UINT16LE||animCount||Number of animated tiles|
|WR_COORD16||animations[animCount]||Animated tile coordinates|
|UINT16LE||fgCount||Number of foreground tiles|
|WR_COORD16||fgTiles[fgCount]||Coordinates of tiles the player should walk behind instead of in front of|
For Math Rescue, instead of reading the 7 letters, the following data should be read:
? UINT16LE iCount7 (garbage trucks) +2 VECTOR[iCount7] ? UINT16LE iCount8 (teleporter) +2 VECTOR[iCount8]
Let a VECTOR be defined as follows:
+0 UINT16LE iStartX +2 UINT16LE iStartY +4 UINT16LE iEndX +6 UINT16LE iEndY
The WR_COORD data type is defined as follows. As shown above it is preceded by a count, and then repeated that many times. If the associated count is zero, the WR_COORD structure is omitted entirely. WR_COORD8 values are in units of 8×8 tiles, while WR_COORD16 values are in units of 16×16 tiles. A WR_COORD8 value of (1,2) will be at pixel position (8,16). A WR_COORD16 value of (1,2) will be at pixel position (16,32).
|UINT16LE x||X-coordinate (in tiles)|
|UINT16LE y||Y-coordinate (in tiles)|
Each DRIP_COORD is the same, but with a drip frequency as well:
|WR_COORD8 pos||Drip origin. Should be directly below an open pipe tile.|
|UINT16LE maxY||Maximum y coordinate of the falling drip. Falling below causes the drip to appear at the initial position again.|
The background layer of map data follows next. The data is stored in a basic and quite inefficient RLE coding. Data is stored as a pair of two bytes. The first byte is a count (often one) and the second byte is the value to repeat that many times. Values (second bytes) of 0xFF refer to transparent/background tiles. After expansion there will be mapWidth * mapHeight bytes/tiles.
Immediately following this is the attribute layer, again RLE compressed in the same manner. This layer uses 8×8 tiles instead, so after expansion there will be (mapWidth - 1) * mapHeight * 4 bytes/tiles. The tiles are positioned from X-coordinate 1 (rather than 0), so it is not possible to place tiles in the first column (where x is zero). However because the tiles are 8×8, those at x=1 still overlap the 16×16 background tile at x=0.
The level entrance and exit are also specified in units of 8×8 tiles. The entrance coordinates are of the bottom-middle of where the door image is drawn, and where the player's feet will appear. The exit coordinates are of the top-left of the door image. The door image is 32×40 pixels in size.
The tileset used is specified in the header (see above.) Each tileset is a 320×200 16-colour PCX file, divided up into 16×16 tiles.
The tile code in the background layer refers directly to an index in the tileset (so a value of 0 refers to the first 16×16 tile in the PCX file.)
Animated tiles are simply a list of coordinates (in the 16×16 space) of which tiles should be animated. The animated tile uses the tile placed in the level at the given coordinates plus the next three tiles to the right of said tile in the tileset image. The tiles must be located in the same line in the tileset due to the way this game stores tile graphics in memory and draws them.
The tile codes in the attribute layer seem to be constants:
|0x00||First question-mark box|
|0x01||Second question-mark box|
|0x02||Third question-mark box|
|0x03||Fourth question-mark box|
|0x04||Fifth question-mark box|
|0x05||Sixth question-mark box|
|0x06||Seventh question-mark box|
|0x74||Standing tile (can jump up through it or press down to fall through it)|
|0xFD||Unknown (end of layer?)|
The tile attributes for Math Rescue are:
0x00 - "empty" tile 0x01 - "ladder" tile 0x02 - blocking tile 0x03 - sloped tile \ 0x04 - sloped tile / 0x69 - number icon
This format was reverse engineered by Malvineous and K1n9_Duk3. If you find this information helpful in a project you're working on, please give credit where credit is due. (A link back to this wiki would be nice too!)