Q3A is Quake III Arena in short. OpenArena is a free game derivated from Quake 3 Arena. You don't need Q3A to play OpenArena. Many mods created for Q3A work also in OpenArena.
For more info, please read:
Ad blocker interference detected!
Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers
Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.