Because there is no 64bits Savage XR, the installation is a bit difficult on 64bits systems.
Here are the dependencies you will have to install.
Savage XR needs some packages you can get only on AUR, so use yaourt all the time.
Maybe you will need more packages. If you have a message like this :
./savage.bin: error while loading shared libraries: libXpm.so.4: wrong ELF class: ELFCLASS64
You should google something like "lib32 xpm" to find out which name of package you need (or try to install lib32-libxpm or lib32-xpm with yaourt if you cannot wait, here lib32-xpm is the good name).
yaourt -S lib32-libxmp lib32-libxft lib32-libxinerama lib32-lib32-glibc lib32-glib2 libjpeg6 lib32-sdl lib32-pcre
Remember, if the game doesn't start, use the console to get the problem and google for the good package name.