Comment 23 for bug 1651561

Solution for those that need hand-holding:

1) Download the 16.04 LTS version of ioquake3 from one of the links listed here:

https://packages.ubuntu.com/xenial/amd64/ioquake3/download

2) Extract the game data

cd /tmp
mv ~/Downloads/ioquake3_1.36+u20160122+dfsg1-1_amd64.deb ioquake.deb
ar x ioquake.deb data.tar.xz

3) Extract the data file

tar Jxf data.tar.xz ./usr/lib/ioquake3/ioquake3

4) Put the data file in place

sudo mv ./usr/lib/ioquake3/ioquake3 /usr/lib/ioquake3/ioquake3

5) Clean up

rm -fr ./usr ioquake.deb

6) Profit.