Lights flicker alarmingly across the mansion. There's a low level hum, gradually growing more audible. Power sockets flicker sparks of blue. You might hear the echoes of a mad cackle through the halls.

And then the power goes out.

Your lights are out, your microwaves and fridges are useless... as are your watches, your torches and your laptops. That's odd. They weren't even connected to the power grid.

...and for some odd reason, it's suddenly dark outside as well.

[It was started by the sparks, but the mansion's joined in the fun as well. Nothing electrical works, except for the players. All you robots and cyborgs and pets and... strange... mechanical... humans? You're good!]