IMC Files (*.IMC)

Combat animation sprite files. Each IMC contains all animation frames for one character body type and animation type. IMC files are accessed through the catalog system (e.g. A00C.CAT contains alchemist IMC files).

Extension: *.IMC
Location: Via CAT archives (e.g. A00C.CAT, E00C.CAT)
Byte order: Little-endian (16-bit) — decompressed layout
Size: Variable — frame-based; CB: 72 frames, WK: 72, DY: 16
Compression: Darklands DRLE — applied to the whole file; offsets below are post-decompress
Magic: None
Status: Partial
Source: Wendigo — X.imc.xml; Olemars — imcfile.cpp

Canonical source: X.imc.xml (Wendigo’s Darklands repo)

Compression

The entire .IMC file on disk is compressed with the Darklands DL-RLE variant. All offsets below describe the decompressed content.

Animation Types

Each filename encodes body type and animation:

Suffix	Frames	Description
`CB`	72	Combat animations (multiple weapon variants)
`WK`	72	Walking animations
`DY`	16	Dying / dead animation

Decompressed File Layout

Header

Offset (non-DY)	Offset (DY)	Size	Field	Description
0x00	0x00	24	(unknown)	Pairs of words; possibly Y/X frame offsets
0x18	0x18	1	(unknown)	`0xFF` for DY files, `0x00` for others
0x19	—	20	(unknown)	Motion-related; all zeroes for static monsters. Present only in non-DY files
0x26	0x1a	2	`sprite_height`	Height (same for all frames)
0x28	0x1c	16	`sprite_widths[8]`	Width per direction (word); all frames in a direction share the same width
0x48	0x3c	2	`frame_count`	Frames per direction; file contains `8 × frame_count` total images
0x4a	0x3e	2	`data_length`	Size of remaining file data after frame offset table
0x4c	0x40	varies	`frame_data_offsets[]`	Word offsets to frame data

Frame Format

Offset	Size	Field	Description
+0x00	1	`width`	Width of this frame in pixels
+0x01	1	`height`	Height of this frame in pixels
+0x02	varies	`image_data`	Row-encoded pixel data (see below)

Row Encoding

Each row:

byte — count of defined (non-transparent) pixels
byte — count of leading transparent pixels to skip
N bytes — palette index values (0 = transparent)

Confidence

Medium-high. Documented in X.imc.xml and corroborated by Olemars’s imcfile.cpp.