Download the Linux installer from [the very slow, but free] IdSoftware.
Interesting Quake4 downloads and updates are found here.
Quake 4 for Linux
￼Quake4 GNU/Linux FAQ
"systemctl status osspd.service" will tell you the current state of the OSS Proxy Daemon. This is used to enable sound from legacy applications which use the OSS sound API. You should install the "ossp" package if you need this functionality.