Install to /usr/games/ instead of /usr/local/bin/.
--- a/chessx.pro
+++ b/chessx.pro
@@ -309,7 +309,7 @@
 }
 
 unix:!macx {
- target.path = /usr/local/bin/chessx
+ target.path = /usr/games
  pixmaps.path = /usr/share/pixmaps
  pixmaps.files = data/images/chessx.png
  desktop.path = /usr/share/applications
