SYGNAS shipped their own file formats on the Lucky★Mas disc, all built in native MSVC-2005 C/C++. The scope doc that started this project feared they were an undocumented dead end. They are not: all three are simple little-endian chunk directories, and every text-bearing chunk turned out to be compressed with an LZSS variant. The fun part is that there are three different LZSS codecs, one per format, and the famous 0xFF byte that begins each compressed blob is the same red herring in all of them.
The .mink files (<char>_copy.mink, <char>_dl.mink, around 4.8 MB each) hold the MinkIt engine's copy/download animations. The header is a 16-byte record followed by a chunk directory; each entry is an 8-byte NUL-padded name, an absolute offset, and a size.
| chunk | what |
|---|---|
| info | per-character metadata, LZSS-compressed (Title, Author, Pattern, Interval) |
| a0 | sprite / atlas stream (around 3.0 MB) · codec still open |
| m0 | mask / per-pixel alpha stream (around 1.85 MB) · codec still open |
The info chunk decompresses to a tiny cp932 INI. An earlier note guessed it was a fixed codec table; decompiling MinkIt.dll proved it is genuinely per-character, read by GetExtraInfo which scans for Title= and Author=. The English patch rewrites just Title= and leaves a0/m0 byte-identical. The sprite codec (header 38 47 03 01 ..., identical across every file) is the one hard task left, but it carries no text, so it does not gate the translation.
23 .Xvi files, magic ACZ\0, a 32-byte directory record per entry carrying a name, offset, stored size, uncompressed size, and a tag whose low byte flags stored vs compressed. A character decomposes into two stored PNG frames plus a compressed Ini blob.
That Ini blob is the whole point: it decompresses to the character's speech config, the [POS] sprite and bubble layout, and a [Msg] block of Serif* dialogue lines (with \n breaks and <%VAR%> templates like <%SCHEDULE%>). Decoding all of them extracts the launcher's entire text surface: 22 characters, around 220 dialogue lines, as editable Shift-JIS INI.
Magic PACKDATA, a 44-byte directory record per file, 115 members: 111 PNGs (stored) and 4 Squirrel .nut scripts (compressed). calmain.nut holds the unit-conversion tool's display strings; the calculator button labels are baked into the PNG skins, so they were re-drawn rather than edited as text.
Every compressed blob starts with 0xFF, which looks like a format marker but is not. It is simply the first control/flag byte: the ring buffer starts effectively empty, so the opening 8 tokens are all literals, so the first flag byte is always all-ones. Past that, the three codecs genuinely differ.
ACZ Ini = canonical Okumura LZSS
ring N=4096, max match F=18, THRESHOLD=2,
ring pre-filled with 0x20, flag bit SET = literal.
byte-exact on all 22 launcher files.
PAK .nut = a different LZSS. control bits read MSB-first,
bit SET = literal. match token is 2 bytes:
length = (b0 & 0x0F) + 2 (2..17)
distance = ((b0>>4) | (b1<<4)) + 1 (12-bit window)
the distance low nibble sits in b0's HIGH nibble,
which is why a single contiguous bit-split misses it.
overlap-capable (RLE).
.mink info = MinkIt's own bit LZSS. bits MSB-first.
0 = literal (next 8 bits = a byte)
1 = back-ref (8-bit distance, then 4-bit length)
256-byte window, fields raw (no +threshold).
terminates on source-EOF, not a count.The .nut distance split was the puzzle: a brute force over one cut point and both byte orders found nothing, because the field is non-contiguous. Working three back-reference samples by hand (0xa0 / 0x60 / 0x10 decoding to distances 11 / 7 / 2) gave away the (b0>>4)+1 relationship. The .mink codec was recovered the harder way, by decompiling the decoder and bit-reader in MinkIt.dll and porting them byte-for-byte.
All three codecs round-trip byte-exact on the owner's own originals (encode then decode equals identity), and each has a self-test. The only un-round-tripped piece is the textless .mink sprite stream, which is stored verbatim. Full field tables, offsets and the decoder pseudocode are in docs/mink-format.md; the unpacker and repacker are sygnasunpack.py and sygnasrepack.py.