Hello.
The game so far is interesting.
The worldbuilding is limited but well done.
The characters are few but well described.
The story is still short but easy to understand.
I'm not into 3dcg but the result is fine. The background is beautiful, particularly the water that feels real. I'm less sure about the sperm that looks like plaster. Mathew's face makes me think too much of a zombie.
The relationship between Mathew (I prefered when it was still Mathieu) and Fabien is cute. Though I think that a character like Mathew, that only focused on his studies, became too quickly obsessed sexually. Fabien is a jerk but it's never nasty.
Carlos, even though we know him since recently, is also a nice character. Plus, it's fun to see Fabien and Carlos teasing each other.
The uncle is too straightforward, he lacks subtlety. During the camp, when talking with Mathew, his facial expressions were ugly, sorry to say it like this. He was correct at the house though.
You've succeeded by putting the incest in the background to make it not too heavy.
You shouldn't have ended on that cliffhanger...
Good continuation.