A phenomenal mystery game where you never get stuck and your players are always getting one step ahead of where you expected them to be with smart deductions and judicious use of Eureka! points to resolve previously failed rolls. Luckily, this game also has a bespoke combat system that's high stakes and fun while simultaneously extremely punishing for sqiushy humans. Every time my players found themselves somewhere they shouldn't be over the course of our eight-session mystery, they saw huge rewards in terms of clues and huge costs in terms of severe injury and genuinely life-threatening danger. 

The modules are probably a ton of fun but I got into this game because I always want to write a mystery for people to play in. If you feel intimidated writing one yourself, absolutely use a module, but if you, like me, found yourself writing intricate, thematically-rich mystery adventures with complex and three-dimensional antagonists that never quite fit neatly into any other games you'd tried to run, this is the best game I can imagine to finally find what you've been looking for. Don't be intimidated by the page count, but there is a lot of complexity, so be ready to prepare rules reference guides for your players, particularly for combat and composure.