Marble shows golf courses, but miniature golf courses are not rendered correctly currently. The goal of this task is to implement miniature golf course extraction and rendering in the same way as a a golf course. There is an icon data/svg/osmcarto/svg/leisure/miniature_golf.svg in the Marble git repo that can be used (make sure to update to latest master).

The tagging of miniature golf courses is explained in https://wiki.openstreetmap.org/wiki/Tag:leisure%3Dminiature_golf