The specific case is, imagine something buried in a part of the ground that is exactly the same as the rest, there is no difference. Or a passageway under a carpet.
The player uses the left mouse button to move around and also to activate events by clicking on them. In the cases I mentioned, you may click accidentally, as both are part of the terrain you can walk on.
However, with the keyboard, you have to position yourself exactly where you want to ‘interact’ on the terrain and press the ‘action’ button, which is different from the movement button.
Therefore, to leave mouse input enabled, what I am going to do is try to modify the behaviour of the left click. It should be used to move, but it should be separate from the action button.
I hope I have explained myself clearly...