What reminded me most of Dickson Carr here was the use of two related crimes that shed light on each other, the locked room tricks, and, of course, the false solutions. The false solutions were handled fairly for the most part, and it was a good authorial choice not to dwell on them for too long.
Several contradictions, however, are exactly the sort of thing Enth and I parodied: hidden assumptions are needed, the contradiction is a matter of opinion or conjecture, and so on. The early badge contradiction stalls the case's momentum badly for several reasons:
* We need to assume that the guard's memory works like no human being's memory does. Even "photographic memories" are reconstructive, and seeing someone with a slight change in their clothing later on can influence recollection. The comment about how Helene seemed like a lawyer could, barring further edits, simply reflect on the guard's current state of mind. "I saw she was one of those crazy lawyers" would be more fair than a comment about how lawyers dress crazy; it's a subtle distinction.
In addition, chloroform is not something it's easy to carry around without notice on a cloth. It's volatile and smelly and dangerous. That the guard didn't see any chloroform bottle, or smell the scent of it, is more severe of a contradiction than the badge.
This comes back to haunt you later when "needing to dispose of the chloroform bottle" is a step in Henry's plan that would allow him to be caught, but isn't addressed.
* At one point, it's necessary to present the lighter to show that a fire was happening at a certain time. Presenting the fire alarm that went off at that time? Penalty!
* The general reliance on memory contradictions without any link to the CR is extreme in the absence of a mechanism for revisiting earlier scenes. There's nothing on the level of the window-washers here, but it gets very close. In addition, no explanation is given for why the maid's prints on the fire alarm aren't a valid answer to what is otherwise a crazy memory contradiction. Other answers that seem plausible but are wrong: Helene identifies the pendulum as a "Foucault pendulum" even though the CR says "pendulum" only, and the room was kept locked and private.
* One possible way to reduce the need for detailed memory on the lighter would be to explicitly mention how the detective added it into evidence in its CR profile. Another, more pointed way: Instead of "probably belongs to Regina," try, "According to Detective wossname, nobody at the scene recognized it." This reminds the player that the maid handled the lighter without SAYING so.
Obviously, if I can't even remember the DETECTIVE'S name without the CR open in front of me, I'm not going to like that puzzle as is.
* This is doubly important when the penalties get huge. A mysterious videotape that's supposed to prove something and could very well be a security video, and massive penalties for presenting it to compare to someone's face? Either a notice should be added that the video doesn't need to be used yet, or a special convo should be added to deal with video presents in that cross-exam.
* Helene takes off her sunglasses in that final exam, revealing that her eyes have a different color from Titania's, implying contacts. You do not want to know how many times I got penalized trying to prove this. In a case where I'm expected to be obsessed with detail, it's kind of frustrating to lose because you noticed one.
* At the time the key swap is presented, there's a solution that isn't recognized:
1) Plant key to another apartment/fake key/old key on body before room is opened, use victim's key to leave and lock door.
2) Swap it out after body is discovered with the victim's key.
In this case, the killer would need to access the body briefly during the investigation, and it's not as elegant as the "don't return the spare" solution.
That said, there's another issue, which is that there's no reason (at that point in the trial) for the player to believe that the key from the old case would really be used by the murderer, when any other fake of a similar make with a similar tag would do.
* The smoke detector stretches fairness to the limit, and possibly beyond. Why wouldn't he wipe the prints on something he touched in the room? What if he just pushed the button that resets it, rather than removing the batteries? The added misdirection raises the difficulty from "very hard" to "totally brutal." I solved it without hints, but could not believe THAT was the answer even as I presented it.
One issue is that there's a lot of misdirection here. For one thing, how on earth were the ashes on the key faked convincingly after the prints had been wiped? For another, was Henry wearing clothes that were totally flammable, all the way to the shoes? Nobody noticed that? What about parts of his costume that don't normally burn, like his badge or bracelet, where a luminol test might reveal blood?
* In one testimony, we effectively have to say "I am ignoring these claims and raising a difference of opinion, not a contradiction, because my story can't explain X and you are giving it too much credit." This is... stretching the way contradictions work pretty far.
* Only the key proves it wasn't self-defense? Not... the autopsy report showing repeated stabbing after death? The knife taken from the kitchen (BP cleared up later that this was because OBERON attacked with the knife, but that's ambiguous at first)?
Even the chloroform gives an instant game-over-retry. Really?
"Oh, sure, I always carry around chloroform in case someone attacks me and I have to frame someone else! Yep, NOT PREMEDITATED!"
Pretty much the entire CR - at least, things related to this incident - show that it wasn't self-defense, whatever it was.
That said, there were some truly great puzzles here, as I said in the review above. Both locked rooms were quite good, and the last locked room puzzle with the key swap was elegantly done.
For the locked room trick, there's no way to really eliminate a Numa + Henry collaborative attack. I suggest the following lines:
Henry: "If you're going to pull accomplices out of nowhere, you'd better be ready to back that up."
Helene: "I don't need to. This trick was possible without any accomplices!"
* The houseplant contradiction early on isn't really a contradiction. It asks us to accuse the witness of being either mistaken or lying about Oberon's vacation on the basis of the houseplant... but that's not really true at all. In short, it means forcing the player to make an obvious mistake - the assumption that Oberon wouldn't ask someone to water the plant. Combined with the misdirection in the testimony, it's clear why many players find it iffy.
There's a way to resolve this, though, as I discussed with BP on Xat. Pressing Mint about the spare key could raise the question: "And you never used the spare key before? Say, during the week Oberon was away?" And Mint would reply: "Of course not! Why would anyone visit an empty apartment?" Add this to the testimony.
This would ACTUALLY contradict the plant's survival. If nobody visited, then it would have been dead. Now, the next problem becomes: how do we get to the "plant swap" theory if Helene already is raising the possibility of a visitor? There are several ways. Here's one possibility I raised to BP:
Henry: "The security office keeps records of the spare key. She never borrowed it."
Helene: "Well, maybe some unknown person used it!"
Henry: "I've checked that, too. I can assure you that the only people to visit the apartment were us three."
Helene: "(...Wait. Maybe I was too hasty here.)"
Helene: "(Is there another way to explain why they saw a live plant instead of a dead one...?)"
Since this is basically a list of suggestions you've given us... I'm just going to edit your post and put stuff here so it's all in the same place for the time being ^^"
-Every time the player fails on the final testimony, add in a bigger hint (since they're guaranteed 3 tries)