You want to revenge the ones that killed your parents twenty years ago.
You need to find your Mosin-Nagant. Use the table against the back wall to find the lamp broken. When you fiddle with the lamp, a panel in the floor moves away and reveals your rifle. Use the opening in the floor to take your weapon. Then you will go to the site where the attack has to take place. But when you aim, the sho0ter gets shot.
Game source: A copy of the game was found here on the internet.