Unity Game idea

I have been considering starting working on a new type of game. I can choose between trying out making everything from scratch with C++ and GLFW, which is totally possible for a Windows game. However, I feel like I really want to speed-run a game. So, since I have quite a bit of experience with Unity from various school projects, I will probably want to use that. Now, I am having a hard time coming up with a game idea. Well, there is no issue with coming up with a "game idea", but I want an idea that I believe will be easy to make and also great. Intuitively, it feels like I am going to have text dialogs if I make a game. Text dialogs that will remind users of Ace Attorney or VA-11 Hall-A. Now, as for the game idea. I want the user to have a lot of freedom in making choices. In short, the game could be like Ace Attorney in that you have to investigate and deal with defending people in court. The main difference is that the player would walk around in 3D when investigating and be a corrupt lawyer that tries to prevent justice by forging evidence and other shady things. I believe it could be fun to let the player play as the bad guy instead of the hero. I suppose I will start out with getting a decent text UI going in Unity as a first step. Then I will create a level where a player can walk around and interact with objects by examining them. Perhaps for certain objects they can be examined by using the right mouse button to click and from there have more options. This is basically how RuneScape usd to handele interaction with game objects.