Never hide the genre from the players. It has never, and will never, go well.

Imagine if a movie sold itself as a slice of life comedy, but when you came in, it was actually a slasher film. You wouldn’t be particularly thrilled that you devoted 2 hours to a movie that was totally different than what you intended to watch, even if it was a good movie.

Players have it even worse. For one, players, for obvious reasons, get invested in who their character is and watching that play out. It’s really annoying when they set up a mundane character in a mundane world with mundane problems only to be wrenched away on a quest to stop Cthulhu from whatever he’s up to these days. Why would they constantly devote 3-4 hrs of their day to a setting they didn’t sign up to play in, instead of just looking elsewhere.

Now, if you tell the players, but their characters don’t know, that’s fine. Great, even. But don’t do a total setting and genre switcheroo on your players. They will feel betrayed and duped.