First of all thanks to posts from Cappy in Ubuntu forums….
While running Alien Arena in Ubuntu 10.04(64 bit) , if you get an error like this one
./crx: error while loading shared libraries: libXxf86dga.so.1: cannot open shared object file: No such file or directory
Do the following.
1. Download getlibs from here and install it
2. Run the following commands
sudo getlibs -p libxxf86dga1
sudo getlibs -p libcurl3-gnutls
Now your alien arena will start running.
Hope this helps.