Hi all,
Maybe I’m starting this topic a bit late, but I wanted to share some Halloween experiences/ideas with you guys. There are enough serious topics on this forum, so a lighter (or scarier) topic is a nice change. 
This the “Halloween mode” I’ve set up. I used it to seriously scare some of my guests who I invited for dinner. In terms of rules, it’s all pretty simple. Maybe you have some creative ideas for next year? Feel free to share your experiences or ideas!
Ok, here we go:
- A few minutes before the arrival of my guests, I turn on “Halloween mode”;
- All guests (and hosts) receive a text message saying something like: “Due to some disturbing events, we recommend not to open doors for people you do not know. We will keep you informed. Kind regards, your local police officer.” (it’s more convincing in the local language). The text messages I send are coming from a generic service number (the same Whatsapp is using to send verification codes), so there is no trace back to me.
- Guest enter (front door opens), a timer is set;
- After two minutes, the doorbell chimes (guests are in the living room then). Strange, I wasn’t expecting other guests. I open the door, nobody is there. As soon as I close the door, the doorbell at the other door chimes. Very strange, also here there is nobody showing on the camera. How are these prank kids doing this?
- I go back to the living room, telling my guests kids are playing some pranks, but I don’t get how they could avoid the camera.
- At that moment, all lights & TV go off (set by timer - x time after I went to the other door). A power outage?
- The all-off is fired every second. So when I try to switch the lights back on, they are turned off almost immediately.
- At that moment, we notice that the light in the garden shed is on (guests have a clear view on that shed from the living room).
- I switch off that light using the light switch next to the back door.
- 2 seconds later, the light is back on. Is there someone in the shed?
- I switch off the light, and now almost immediately, the light is switched on again.
- I tell the guests I go to the shed “to tell these kids to go elsewhere”. One of my guests told me to stay in and call the police.
- As soon as I go out trough the back door (at that time, all lights are still off in the house), and I close that door, all the lights in the house are switched on and my Sonos plays the sound of a machine gun at maximum volume (for approx 5 seconds). This is where my guests screamed for a few seconds, and then realized it was coming from the Sonos and it was all a prank.
- After the machine gun stopped, my other Sonos (upstairs) is playing a creepy laugh at maximum volume.
- I go back inside. While my guests are getting back on their feet, I dramatically say “Computer, turn off Halloween simulation” (Alexa). All lights go back on again, and some relaxing music (at normal volume) is played.
All of this was approx. 1 minute of Halloween fun.
Tips/best practices:
- Make sure your set-up is automated. It will be suspicious when you are doing stuff on your phone while scary stuff happens around you.
- Be kind to pets. Pets can get scared too! If you are working with loud sounds, make sure your pets are not around or can deal with it. A few minutes of Halloween fun does not balance out with a traumatized pet.
- Make sure your guests aren’t holding drinks or anything they can drop.
- Know what your guests are able to “take”. Something that is scary and unexpected is much scarier than something that is scary and expected.
- Be a non-believer yourself. Write the events off as some pranks by kids in the neighborhood (and wonder how they were able to send these text messages);
- If your friends know that home-automation is a hobby, it will be harder to convince them.
- Set up a webcam at a strategic location. It’s priceless to have your scared guests on tape.
Feel free to share your experiences/ideas! Let’s take it to the next level next year. 
There’s always next year.