Vampire invasions are coded to occur in all residential Worlds that existed at the time the Vampires game pack came out (Base Game Worlds, Windenburg, San Myshuno, and Forgotten Hollow) but either due to an oversight or intentional omission, they were never added to newer Worlds, starting with Brindleton Bay. If you mostly play in newer areas of the game, you would never see one.
This mod does several things. First and foremost, it adds vampire events to all Worlds. This includes a small chance of invasions, as well as normal vampire walkbys and the "fake vampire" walkbys at night. There is about 1% chance per night for invasions, give or take some depending on the World you are playing in.
Second, I added modifiers to invasion odds based on certain circumstances. If there is a full moon, the chances of being invaded go up. If there is a werewolf living in the home, the chances are halved.
Third, I enabled invasions in Haunted Houses and Tiny Homes. Previously, these were disallowed even in Worlds where invasions could happen.
Fourth, I've streamlined the event to avoid wonkiness. Invading vampires will show up in front of your house instead of at the edge of the world, they are allowed to show up even if your game is running at Super Speed 3, and there is no longer a time limit for the event.
Requires the "Vampires" Game Pack.
Discord Server & Mod Support
For questions about the mods and troubleshooting, the best way to get ahold of me is the Sim After Dark Discord server. It is a joint mod support server for LeRoiDeTout, Shinobu Nox, NC4T/Keke, and myself. It is a lively server that offers troubleshooting for our mods and others', as well as discussion about The Sims 4.
All my mods are free to download and will remain so, but if you'd like to support me you can pledge to my Patreon where I occasionally post progress updates and exclusive access to beta versions of my newer mods.