Pushing the edge even more. What do we need?
1 - Indentify what is land and what is sea for CV ops.
2 - Terrain heights.
3 - The grid and coordinates
4 - Plane dots
5 - field/factories/Hq icons
6 - Activity bars
Points 1, 2 and 3 are fixed and may be all covered in a 16 colours (4 bits without palette) singlecolor-scale bitmap. For example:
colour 1 - Darkest base colour: 0 feet (sea level)
colours 2 to 14 different base colour tones based on heights up to 13k, each one indicating 1000 feet elevation.
colour 15 - Lightest base colour for any terrain heigh above 13k.
colour 16 - black for grid and coordinates.
This way we have a map based only on terrain heights, it may be grayscale or not, but It need to use a single base colour: grey scale, blue scale, red sale or whatever doenst interfere with icons, dots, bars and grid colours. They player would be able to choose the base colour that better matches his eyes for the entire map.