I'm using this since some time - at most for OpenTTD, but it should work the same way for almost every game or app data you want to keep in sync on your desktops&laptops.
Tested as always only on Linux, 2 easy lines in the terminal and you're done:
n@desktop:~$ mv .openttd ownCloud/my-openttd n@desktop:~$ ln -s ownCloud/my-openttd .openttd
Done on the first computer :-) On the second (and possible third, fourth, ...) please delete the directory if it exists and then repeat the second line of computer one: