Note on the high score files:

The high-score files are kept in /var/games/xbomb and are named
xbomb3.hi, xbomb4.hi and xbomb6.hi (for triangles, squares, and
hexagons, respectively).  These files are all writable by group
"games", and xbomb is sgid "games" so that it can write to them.

If you want to change the permissions on xbomb, you should be aware
that these files must match -- they must somehow be writable by
xbomb.  If they aren't, you're on your own.

In earlier versions of xbomb, the /var/games/xbomb directory was owned
by root:games, and was group-writable.  This is no longer the case, so
xbomb cannot recreate these files if they disappear (assuming it ever
could, which I've never tested).

You may also want to know that these files are not technically part of
the xbomb package.  They are created by the post-install script if
they don't already exist, and removed by the post-remove script when
you purge the package.
