In the "Curtains Down" mission, the player may access the locked door in the upper corridor (the one the worker with the screwdriver is trying to enter) by killing all the rats in the large basement room that has the long sideboard in it. Shortly after the last rat's death, a golden "Rat Casino" key card will appear on the wooden sideboard. This key card will open the otherwise locked door to reveal a small room divided by bars behind which a group of rats are boxing and playing poker.