Oh, it's that time of year, isn't it? When I ought to have dusted off an itch.io link, like, a week ago, and gone:
Shub-Rhadaman is a small TTRPG adventure module, built for D&Dlike games but without any great reliance on specific mechanics, which opens in media res with adventurers waking up shanghaied on a one-way trip aboard Shub-Rhadaman, the Train to the Land of the Dead. If you don't stop the engine before it gets there, you're going to a bad place.
It's short, it's seasonally appropriate, it's a one-shot or a way of throwing a new party together with an immediate common cause; and it's Pay What You Want, ergo free.