I would love to see a mod based on the early part of the Mahdist war (1881-1885). I believe there was going to be a general one that would include the Afghan, Mahdist and Zulu Wars but that became the Anglo-Zulu War reloaded (the mod I play the most may I add).
If there ever was one to be made it would be best to have three factions, Britain, Egypt and the Mahdists. Britain fought Egypt during the Urabi Pasha revolt so that conflict would be represented as well.
The Mahdist War is quite an interesting one as there was such a mixture of uniforms used by the British Army. Some regiments fought in red (the last war in which it happened I believe, save for the odd individual or small unit in later conflicts), others were in grey uniforms, some in khaki made in Britain and other regiments were sent from India wit their India style Khaki uniforms, not to mention it was the first war in which we brought in large numbers of troops from around the Empire, including Canadians, Australians and Indians.