I'm going to have to write this into one of my prospective TLs now.
First, a slightly-longer slavery, along with four *Mfecanes (Sahel, East, Central, South) and no Great War for extra-long Imperialism. And then decades of ideological proxy wars led by postcolonial dictators.
Highlights include:
Some durable states lasting: small Xhosa kingdoms Pondoland and Fingoland, the Tswana Ngwato kingdom, and not much else, at least in southern or central Africa. And even then they'd be proxies.
An even worse cattle-killing among the Xhosa
Slave trade out of South Africa for a few decades (maybe 1760s-1800), leading to even more violence
No German colonies- instead, massive Franco-British cold war with a number of minor colonies
Filibuster Congo
Private German company colony somewhere, no German government involvement
More cults/millenialism
More coolies and eventually coolie rebellions/wars with natives
A Mahdi not in the Sudan
and much more incalculable human suffering. I'm terrible.