I'll consider that idea, no guarantees though.
Something I have done though... check the saved image.
Although not apparent from this pic, nothing in the original graphic set has been removed; I expanded it to allow more than 64 pieces (up to 128 terrains and 32 objects). The somewhat weird placement is because I haven't added support for it to the editor yet, so I had to hex edit these into a level. (EDIT: It's supported in the editor now.)
RGB-based colors is also supported (not shown in pic). They still need a defined 16- or 32-color palette, for the purpose of brick color, and certain colors in lemming animations, but the terrain pieces and objects aren't limited to using the palette.
It's possible I might backport this to Traditional Lemmix. It's not overly difficult to implement.
For anyone wanting to implement support for these extensions into other engines/programs:
- For extra terrain/objects, at the end of the GROUNDxO.DAT file, the same format is repeated (it even includes a second set of palette entry bytes, though these obviously are unused).
- For RGB values, 0x40 is added to the usual flags byte, and all images are read as 19-bit, the 19th bit being an alpha bit. (The mask location is not to be used in this case, and should not be assumed to be accurate.) As usual, each pixel is an 18-bit color, not a 24-bit one.
In NeoLemmix LVL format, the higher ID numbers can be used directly. For traditional Lemmix format, the terrain ID number can't be; still need to come up with a workaround for this.