Joey Joystick is a computer programmer. While he was in his final year of university studies, he worked as an intern with a local electronic games producer, Great Games Pty Ltd. Joey impressed his supervisors with his insightful comments and other input on design work. They were so impressed with his work on one design, Crypt Force, that they gave him part credit for it and paid him a general bonus for it. Crypt Force ultimately won an industry award and proved to be a big seller for the company. 

After Joey's university graduation ceremony, he was ushered aside by a Great Games executive who showed him a document and said:

"We're very impressed by your work, Joey. We'd like you to join us permanently we're sure you'll be happy with the deal we can offer you."

The document was a contract of employment which contained the following clauses: 

1. The duration of the contract is three (3) years.

9. The employee (Joey) agrees that he will not for the duration of the employment contract or for a period of one year after the conclusion of the employment undertake design activities in Australia for the purposes of the production of electronic games or any other form of entertainment.

The starting salary under the contract was that normally paid to a senior designer, which was a position a new designer would not usually attain until he or she had worked with Great Games for three years. Joey happily signed the agreement.

After two years with Great Games, Joey was approached by a film production company, Computer Animated Films Inc (CAN). Joey agreed with CAN that, for a salary five times what he was getting paid by Great Games, he would immediately start work as part of a team producing Cosmic Armada, a feature-length computer animated film. As part of the deal, Joey would also work on a spin-off Cosmic Armada electronic game.

Advise Great Games whether it can prevent Joey from working for CAN.

In answering this question, you are expected to draw on legal rules, principles and cases discussed in the lectures from Weeks 1 to 4 and the corresponding chapters from the prescribed textbook.