What is this African bug?
Based on the long legs and long antennae, I'd say you're correct that it's an orthopteran, very likely a cricket or one of its allies (i.e., suborder Ensifera).
Within this subgenus, the most likely candidate families are either the &quot;true crickets&quot; (Gryllidae) or &quot;camel crickets&quot; (Rhaphidophoridae).
Your photo is not nearly good enough to begin making more informed specific guesses. However, If I had to guess, it could possibly be a cricket in the genus Phaeophilacris, which are striped-leg crickets found in Africa.

See inaturalist for incidence of this genus in Africa.

You can see some photos of Phaeophilacris Bredoides here, with a few photos copied below:
 
 Source 
You can read an interesting paper about communication in this genus here1

 1. Heinzel, H.G. and Dambach, M., 1987. Travelling air vortex rings as potential communication signals in a cricket. Journal of Comparative Physiology A, 160(1), pp.79-88.