Bushka's 'capture by approach' originates in Fanorona, a game from Madagascar. Bushka looks like Jeu de Dames aka International Draughts/Checkers, and has indeed structural similarities, but it is a very different game, far more flexible in terms of development, and allowing positions that are quite unlike those found in the latter. In Bushka, as in HexDame, three kings against one is a win.
 
A complete illustrated description of the rules is included in the download.

Bushka is just one of the games invented by Christian Freeling; they can all be seen, and some of them played, on the internet in the MindSports ArenA.