The Quake 3 engine is open source. The Quake III: Arena game itself is not free. You must purchase the game (steam, gog) to use the data and play Quake 3 with ioquake3. If you do not want to do that you can play another game made with ioquake3.
You can download an ioquake3 test build for:
This Windows build is not code-signed and you may see a warning message from Windows smart screen similar to this one:
Windows protected your PC
Windows Defender SmartScreen prevented an unrecognized app from starting. Running this app might put your PC at risk.
That message can be safely ignored. We are working to resolve this issue. Please see this link for technical details.
macOS This is the main test build link, we also have extra builds from developer Tom Kidd:
- Legacy Universal 1 Build for PowerPC, Intel 32-bit and Intel 64-bit
- Universal 2 Build for Intel 64-bit and Apple Silicon (M1)
If your Mac is newer than 2008, you should probably run the Universal 2 Build as it has been signed and notarized. You will see a dialog on the first run, since macOS has detected that you downloaded it from the Internet. This dialog is normal and expected.
You may need to right-click (or hold down the ctrl/control key on the keyboard and click) to access a menu and select “Open” to open the app. We are working to resolve this issue. Please see this link for technical details.