It looks like supertux does have have a valid icon (/usr/share/icons/hicolor/256x256/apps/supertux.png). Perhaps it the fact that it is referred to "supertux.png" in the .desktop file and not "supertux" that is making it not work?
It looks like supertux does have have a valid icon (/usr/share/ icons/hicolor/ 256x256/ apps/supertux. png). Perhaps it the fact that it is referred to "supertux.png" in the .desktop file and not "supertux" that is making it not work?