An act of murder
An Act of Murder is a classic country-house mystery: an isolated estate, a small group of suspects, a limited amount of time to solve the crime.
The country-house mystery premise has been done numerous times in interactive fiction... An Act of Murder stands out because it does ask the player to focus on drawing conclusions: what do you know? What do you need to find out next? What do these alibis mean? There are a few objects to discover, a few pieces of evidence that have to be searched for, but for the most part, Act of Murder is about the conclusions you draw, and how you figure out where to look next.