In the xterm as a normal user, navigate to the directory that contains your game binary.
Example for NFS:U is /home/user/applicaitons/com.ea.xxx/

Example for N.O.V.A is /home/user/applications/com.gameloft.xxx./nova/

Now type: preenv

Then type ./ followed by the binary for your game.
Example for NFS:U is ./nfsuc

Example for N.O.V.A. is ./nova