What error message are you getting?
Try these steps:
1. Move the application to your Applications folder.
2. Open Terminal.
3. Paste
sudo chmod +x /Applications/Mac.app/Contents/MacOS/TheRadiants
(note the file location may be different for each user, so confirm the file path before
pasting)
4. Press Return/Enter.
5. Enter your password when prompted and press Return again.
6. Open the Radiants application.