Running Acorn Chess on an Apple Mac
After downloading Acorn Chess you should have an Acorn Chess installer in the downloads folder on your computer as follows:

Double clicking on the AcornChess.pkg file will result in the following warning dialog.

Note: This message appears as this application and developer has not been officially registered with Apple. This is a standard precaution for apps from outside major app stores. To open this application follow the steps below. |
1. Open System Preferences
You will find the System Preferences application in the Apple menu (top left corner), in the Apple dock or by selecting Launchpad to view all applications.

2. Select Security & Privacy
Having opened System Preferences you should see a dialog window as below. Privacy Security is highlighted below and should be selected.

3. Privacy and Security
Scroll down within Privacy and Security to the Security section highlighted below. It will explain that Acorn Chess was blocked as it is not from an identified developer. Clicking Open Anyway will launch the Acorn Chess installer.

4. Running Acorn Chess after installing
After running the installer when you double the Acorn Chess icon from the Launchpad you will see the following warning displayed:

Again this is because Acorn Chess is not part of the official paid Apple Developer program. Click Cancel and then go back to Privacy and Security in Settings as per step 3. You will see the following warning and should click Open Anyway.

Now when you click to open Acorn Chess you will get one final warning. Click Open. This will successfully open the Acorn Chess application. You will not receive these warning messages when you open it the next time.
