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The original LZEXE (A.K.A. Kosinski) compressor source code has been released

Last year, I discovered that the Kosinski compression format is actually LZEXE, which was used for compressing DOS executables back in the 90s and the late 80s. Its developer catalogues three versi…

Back in 2021, I made my own Kosinski compressor which produced identical data to what could be found in the Mega Drive Sonic games. Notably, the compressor which was used for the Sonic games suffered from a number of bugs and shortcomings, causing the compressed data to less efficient than it should have been. Unfortunately, I do not have much hope of ever finding the original compressors for, let alone the source code of, the remaining two formats – Enigma and Nemesis – due to them evidently being custom formats which were designed specifically for the Mega Drive, likely meaning that the compressors and their source code never left the hands of Sega (Enigma encodes plane map data, operating on 16-bit words and specifically acknowledging the separation of bits of the tile’s index from its X/Y flip, palette line, and priority; meanwhile Nemesis encodes tiles, operating on nibbles and bunching data into groups of 32 bytes (8 x 8 4-bit nibbles).

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