/usr/local/bin/xplanet+
%%LOCALBASE%%/bin/xplanetis OK in most cases for installation from sources, the usual path for installation from precompiled packages is -
/usr/bin/xplanet+
%%LOCALBASE%%/bin/xplanetAdjust the window size (remember to set up a square, ie. 400x400, 300x300 etc. to avoid strange effects). Also, the window position must be set up to create a nice looking screen. Use the Test it!