Valve has announced the Steam Mystery Fest, a sale event dedicated to investigative mystery games. The event will feature demos and discounts for all things "focused on the spirit of investigation and solving mysteries", and it's set to start in February, so get your deductive reasoning hat on.
In the official announcement for the Steam Mystery Fest, Valve invites developers to submit their titles for the event. The studio also provides criteria to check whether or not a game fits the intended spirit of the Steam Mystery Fest, including examples of games that might not fit the bill.
There are three main elements a game can contain in order to be eligible for the Mystery Fest: it has to have some element of mystery (naturally), it needs a focus on detective mechanics, and it can also be themed around social deduction.
Noir theming is popular among detective games, too, so if you're a developer making a noir mystery game, you may well be in with a shot. Think Return of the Obra Dinn, The Case of the Golden Idol, or even more detective-adjacent titles like Backbone (the followup for which is now launching in 2023), and you're on the right track.
Examples of games that might not be eligible include those focusing on combat, as well as spy games, straightforward puzzle games without investigative mechanics, and horror games "that may include a mystery element but that do not focus on investigation". If your game is a walking sim and it's not based on solving mysteries, you're probably out of luck, too.
We don't yet know what games will appear in the sale, but it's a safe bet that the likes of Sherlock Holmes: Chapter One, The Great Ace Attorney Chronicles, and any other game themed around detective work will make an appearance. You'll probably also discover lots of new demos for games you didn't know you wanted, too.
The Steam Mystery Fest kicks off on February 20th and runs for a week. If you're a developer and want to submit your game, the deadline is January 9th. Your game doesn't need to be discounted, but it's more likely to feature on the main sale page if it is. The game will also need at least one trailer set to public.