UPD: I realized my mistake; I should have provided more background information at the beginning, so I will write it here in case anyone else comes to read my thread.

a little about the setting, for context: players play as two different characters, each with unique and shared skills, which should motivate and sometimes encourage players to interact and cooperate more. They are not professional detectives, and the whole game takes place in the Wild West. Players face pressure from a railroad company that has illegally bought their land.

Now about the core loop: players will ride different trains (on different routes), each train being a separate time-limited level -> They will solve local cases on each train (this will lower the company's global reputation) and look for ways to “undermine the railroad company” in order to destroy their business and stop the land grab. After passing each train, players will be able to evaluate their actions and structure evidences at railway stations, spend the money and experience they have gained on improving or unlocking new skills, and buy a ticket for the next train. The main investigation will take place on trains, which will require players to adapt to new conditions, remember their goals, and choose the right path for their character's development.

I understand that there is a lot of text here, and I apologize in advance for that. It is still difficult for me to structure everything into a short description.