I really do enjoy Mert's route. He portrays a mature caring and dotting man quite well. His route is romantic and light hearted which makes it more enjoyable. all that in mind. I'd like to give some criticism. The following points are from my own thoughts and opinions:
1. One route feels more cannon/dominant than the other. It feels like Mert is the "supposed" love interest for Finn. Mert got more screen time than Artyom and that added more depth to his character than Artyom would ever be in his own route.
2. Artyom feels like just an obstacle for the main love interest. As I said in point one, the lack of depth in Artyom's characterization is making me feel like he is a side character who only exists to compete with Mert instead of a genuine second love interest for Finn. He also left with a rude, kind of immature, and competitive man in the introduction part of the story without any reasoning behind his character.
3. The main character favors one more than the others which is kind of bad if you want to make the mc as representative of the reader. Finn's inner thoughts favor Mert more than Artyom. Especially on the first and second days of the story. slightly less in 3rd day which is a good improvement. Finn would always think about Mert at any given time. It is kind of justified considering that Mert did save his life. Although Holger did the same too.Take a look on the second day of the story for example. Artyom tries to appeal Finn's affection by giving him a necklace that he likes while he takes the necklace that Finn likes which is romantic in a sense. Finn's reaction is dull compared to when Mert gave him a bouquet at the end of the day.
4. Artyom romance advancement always got invalidated. On day one he broke it with his rude behaviour. on day two he got shadowed by Mert and on day three he decided to take two steps behind after moving one step forward. This back and forth pattern is not a bad thing. It is actually a great thing if used correctly. It will bring some struggles and slowburns vibes into his story which would give him the depth he needs. although do not overuse it because readers can get tired of the same pattern repeating over and over.
that being said. I really enjoy this VN and I hope that it will be successful in the future.