ioquake3
A legitimate copy of the game is required to play, either bought from
Instructions on how to extract game assets and setting up the game can be found on the ioquake3 Website.
ioquake3 is a free software first person shooter engine based on the Quake 3: Arena and Quake 3: Team Arena source code.
yay -S ioquake3
Copy the pak0.pk3 file from your copy of the game:
# single user
cp pak0.pk3 ~/.q3a/baseq3/
# system-wide
cp pak0.pk3 /opt/quake3/baseq3/