You need to get out of the office.
Turn to the right and click the table leg between the two chairs. Behind the leg is a LIGHTER. Leave the chairs and turn to the right. Look closer at the cabinet and look at the drawers. Open them all and note that some of them have files with names in them. Note the names: Paperwork 5, Document 1, X Files 2 and Assignment 3.
Turn to the right again. Look at the ceiling and find a GOLDEN KEY stuck in the fan. Take it. Leave the fan and look closer at the chair to see the desk. Use the key on the drawer in the middle. Inside you’ll find a safe that needs four numbers. Use the numbers you found on the files in alphabetical order: 3152.
Push the button on top of the safe and a KEYCARD pops out. Take the card and leave the drawer. Use the desk under the drawer to see the slot for the card. Use the card on the slot and leave the desk again. You can now use the door of the cabinet on the right side of the desk. Inside you’ll find a GREEN KEY. Take it and leave the desk. Turn left and look closer at the brown cabinet next to the file cabinet. Use the green key with the left door and find a stick of DYNAMITE inside.
Take the stick and leave the cabinet. Turn left twice and use the dynamite with the frame of the front door. It will blow open and you can leave the room.
Game source: A copy of the game was found here on the internet.