Brilliant game! The merits are obvious - some actual problem-solving skills are needed to complete the game (which is more than what could be said for a majority of games/gamebooks of the same genre IMHO), and it *is* possible to come to a wrong conclusion, which adds to the challenge.
Also, ironically, many of the deductions (such as the conclusion that the killer struck before 2:55) are made using the wrong assumptions, giving the game an authentic real-life feeling.
As for possible improvements, personally I would recommend starting the “sudden death” mode much earlier in the game. Calling the police officer a suspect or prematurely announcing the incident a suicide, for instance, is something which should definitely end the game IMO.
There is a slight detail the author may have overlooked: when Alan is first accused of murder, he produces a piece of glass which has both his and Louis’ fingerprints on it, also mentioning that there is more in the washroom garbage. The piece of glass used to stab Serge did not have Alan’s fingerprints. If the incident was a suicide as Alan described, this could not be the case. That was how I initially deduced that Alan was lying, not any of the options given, which was confusing. Of course, this is only a minor detail that doesn’t affect the quality of the game.