I love Halloween gaming. It’s an awesome opportunity to bring horror into a campaign. I know we don’t need an excuse to bring horror into our games, but players just seem more receptive to it during this time of year. While I generally run a dedicated one-off game fo Halloween (generally Call of Cthulhu or Dread), there are several ways to bring a bit of Halloween into a standing campaign.
Probably the easiest way is to just take the opportunity to do a side story. Side stories are a great way to keep a long-running campaign fresh by doing something totally unrelated. Maybe your D&D party encounters a haunted mansion on their way between cities and is convinced to explore it. Perhaps your Starfinder group stumbles across a derelict cruiser. The tropes of Halloween lend themselves to taking the players to a separate location where you can have a more horror-themed adventure.
But the side trek isn’t your only option. You can always introduce horror as an element of the adventure itself. Perhaps the evil wizards you’ve been tracking has unleashed some horror on the local townsfolk. Heck, you can always just throw in a good ol’ fashioned murder mystery with a supernatural flavor. In my experience, you need to tone down the horror elements a touch when using this approach. At the end of the day, too much horror in a non-horror themed game tends to break the player’s investment in the campaign, so keep the changes relatively small.
The last approach is probably the hardest – the campaign branch. In this approach, you shift the campaign generally over the course of several sessions to culminate in a big horror finish. This takes a lot of planning, but it helps to alleviate the issue with player buy-in. Personally, I don’t care for this approach unless it was always part of the narrative arc, but that’s just me. Where it’s worked best for me is with systems that aren’t necessarily horror-themed, but can easily go down that path, such as the World of Darkness games (Vampire, Werewolf, Mage and Wraith in particular).
Regardless of how you do it, try having a Halloween-themed gaming session. I’ve found them to be among the most rewarding and memorable gaming experiences I’ve had and it’s something I look forward to every year!