Later on in the game, you'll receive a mission named "Earn A Bit On The Side?". Once accepted and you arrive at the job, enter the computer room (the room where you have to place all of the computers). Inside the draw of the cabinet, you'll find the console which looks like a GameBoy. Add it to your inventory and finish the mission.
After the mission is complete, you'll receive an email asking you to fix the aforementioned console. Accept this task, head to the workbench and fix the console. Before sending it back to the customer, hit the 'Enter' button and you'll be able to play a Tetris clone. You'll then need to earn a score of 10,000 points.
Everyone should know how to play Tetris, but if you're struggling,
here's some tips