Hi there, I played the game!
First of all, it looks and sounds really nice. The setting is also promising, so I think you're up to a good start!
I managed to learn that the passport is forged
However, I can't do much about it, it's not a dialogue option etc, so I'm not sure whether I'm stuck or it's how it ends right now?
Anyway, here comes the critique.
The most important part is that I think right now you're not communicating all the necessary information to the player. As a player, I'm not told clearly:
1. What's the main goal of the investigation? What mystery exactly are we solving? Is it Victor's health condition, or something fishy in his past, or something else? As we're told, the main client is Catherine. However, she never tells us her suspicions, her motivation to even hire a detective. There is a safe we want to crack – why? Because we just want to look through all the character's stuff? Or do we believe it contains something we're looking for? What, then?
Why as a player do I need to know this: because otherwise I don't really have an objective, so I don't know what to do. I just do random things that the game allows me to, waiting for it to play itself. I can't use my own logic in the game and have to tag along with the game's own obscured logic instead. That is a feeling of detachment from the game that you really want to avoid for your player.
2. Names and roles of the characters. It's like the protagonist knows who his interviewee is, and the player doesn't. You can do it on purpose, not narrating the story to the player explicitly and let them figure everything out by themselves, but then you should craft it carefully to avoid all the disambiguation. It was puzzling to learn the name of the character from my own dialogue logs. So I don't think it was intentional?
Then, I got a feeling that there were some uncertainties about characters' motivations and the logic of investigation.
1. I didn't get final impression on who initiated the investigation. The telegram was from Catherine. But then we're told that the real initiator was her father. But then we're told the real client is Catherine and we have to play along. Why do you need her to send the telegram then, if she is so reluctant to tell us her reasons to do so? Wouldn't it be easier for Victor to send it?
2. Catherine's attitude gives me mixed signals. At first she is pleasant to us, then when we start the interview with her father, she starts bullying us. It doesn't look organic, is it because she wants to behave like a bully in front of her father? If so, why isn't our protagonist in the least surprised by that drastic change? Then she tells us she will come along with us to the Uni, but when we come she is not there. I thought at first I got to go find her. But then she kind of spawns in the office the second we find a passport?
3. Why do we learn the passport's forged by checking the place of birth? Maybe the passport is ok, but Victor only misinformed the authorities about his place of birth? Also, in the modern world you can't just call a town hall and inquire about some random person. So if you want your player to get that it's OK in France of 1970s, you have to slip it in some way, I think.
4. If we are officially hired by Victor, why do we get scared when someone (Martin) comes into his office when we're investigating?
5. Etc etc
It looks like you as a writer know much more about this world that you let on, so you end up not communicating it to the player, because for you it already makes sense. I think the best thing to do is to create a timeline of when you introduce what, and to make sure everyone and everything (including characters' motivation) is indeed introduced.
I also got a bunch of technical issues if you're interested but since it's still a prototype you probably know about all this stuff yourself.
Hope it helped! Wish you all the luck! Feel free to ask me anything.