Here are my notes on Nancy Drew: Secrets Can Kill (1998).
1. The boiler room puzzle is a good and suspenseful multi-part puzzle. That said, it doesn't make any sense, plotwise. Why did the murderer try to kill Nancy? How does the murderer even know who she is? She's an undercover agent, and furthermore, she's never seen or talked to the murderer. He tries to kill her, at a point in time where she poses absolutely no threat to him.
If you fail the puzzle, the school explodes. No, not just the boiler room: the entire school. The murderer was willing to go very far, in order to kill Nancy.
2. Jake's VCR tape is in the school's vent system for no apparent reason. Who left it there? Presumably Jake did, because it doesn't make sense for the murderer to have left the tape behind.
3. There is a ladder, leading to an area below the boiler room. Nancy can look at the ladder, but she can't climb down the ladder. Presumably, this is the exit that the murderer used to leave the boiler room. Why doesn't Nancy use this exit? The exit is also there in the Remastered version of the game, but you can't zoom in on the ladder.
4. Jake's video shows Connie getting into her car. You'll notice that the front part of the room is there, but the back part isn't.
5. The game breaks the first rule of good detective stories, which is "the culprit must appear in the story". Instead, the culprit doesn't appear or get mentioned, until five minutes before the game ends. It is literally impossible for you to put together the clues and solve the mystery yourself, because the culprit is a complete outsider that you've never heard of.