Cryosphere supports 256 colours outside of screenreader mode.
@@I RGB colour chart

Cryosphere supports the specification of colours from a 6x6x6 colour grid in addition to the usual 16.

Use ^rgbX where r, g, b are integers between 0 and 5, and X is the colour code you want used for people who are stuck with the normal colours.

&-rgbX can be used to set backgrounds.
     |-----------------------------------------|
green|000000|111111|222222|333333|444444|555555|
blue |012345|012345|012345|012345|012345|012345|
red 0|      |      |      |      |      |      |
    1|      |      |      |      |      |      |
    2|      |      |      |      |      |      |
    3|      |      |      |      |      |      |
    4|      |      |      |      |      |      |
    5|      |      |      |      |      |      |
     |-----------------------------------------|

If you are have a terminal that supports 256 colours and the feature is turned on, this will appear as a nice colour cube. Otherwise it will appear as 6 white rectangles.

Cryosphere allows specification of True (24-bit) colours, internally, and in setcol only. See setcol information on how to specify those.

See the display command for how to set your colour mode.

See also: info colour