From the Save a Rhino site:
Rhinos are hunted and killed for their horns, which sell for enormous amounts on the black market. The game Save a Rhino aims at increasing awareness of the rhinos’ situation and raising funds for preservation efforts.
In Save a Rhino, you play as a rhino or elephant, trying to escape from poachers. They’re coming from all directions, and if you don’t manage to snap up some greens while fleeing, you will soon run out of energy.
Save a Rhino tells you about the dangers the rhinos are facing, as well as what is being done to prevent the extinction of the species.