When downloading the Linux demo, there is only an x86 executable available. If you look on Steam's hardware survey you'll see that almost every Linux gamer is using 64 bit already.
However, you could always just include an x86_64 and a x86 build if you wanted too.
Personally I would do the following:
* Include both an x86 and x86_64 binary.
* Include a shell script (called something like "play-watch1.sh" that does the following:
#!/bin/bash
ARCH=$(uname -m)
case $ARCH in
x86_64)
chmod +x ./WATCH1.x86_64
./WATCH1.x86_64
;;
i386 | i686)
chmod +x ./WATCH1.x86
./WATCH1.x86
;;
*)
echo "This game is not able to run on your platform."
;;
esac
It seems you guys don't have any Linux testers, so if you need any other help hit me up.