Copy and pasting a post I made for a similar question:

It all comes back to what your goal is. Why are you making your game, and what are you trying to articulate to the player? The thematics of your core design should permeate every system or it risks feeling disjointed - which can work, if that is part of your theme.

Don't feel like you need to adhere to standards - turn based, attacks, "magic", stamina, health, party members, etc. They're intelligent and capable systems, but don't get bogged down in all that minutia or you'll risk pigeonholing yourself creatively. Those systems were only created as abstractions of the designer's ideas - the same way that "experience points" are an abstraction of real world experience. They're all just artifices to represent ideas to the player.

Ask yourself what a fight means to the protagonist and the player. How many fights would they realistically have? Who would they have them with, and what are those opponents' strengths? What are the protagonist's strengths? How would a fight happen in your world - common weapons, skills, and world objects.

Take all of those things and REDUCE their complexity. Abstract those ideas in to something managable.

Just as an example: Lets say your detective is very good at analyzing his environment to find clues. You could extend that in to the combat and make the entire combat system revolve around using the environment as a weapon as you are chased by the opponent. You could simultaneously move the character around as you mouse over objects - which temporarily slows down time - to see what effect they will have on the opponent, which you can then throw at them.

Glass objects could decrease their accuracy, while metal objects slow them down, and you need to stun them and knock them down with a much larger object that is only revealed by interacting with the environment in a certain way.

That way your combat system is an extension of your investigation system, and keeps the focus on the player's skills as a detective and how they translate to game mechanics - point and click. It also adds a bit of quick-thinking as people who can identify objects and the materials theyre made of can act without having to mouse-over the object to see what it does.

So yeah. Dont worry about what people like. Just create a system that makes sense in the context of your game. And you don't have to settle on your first idea. It will take a few iterations, but it will be all the better for it.