I tried it & it's different & very interesting

I can't say at this point if I'm for mouse-only concept or not, but if we decide to go for it there is just one thing I found to be problematic: the movement slowdowns/gradual stopping. It would be much better if the players movement & knob could be much faster in status switching. If I move mouse to the right the player should start moving to the right & the knob should be instantly all the way to the right, and if I move mouse to the left from that position, the player should instantly stop and the knob should instantly be at the middle of the circle.

The thing is that I was more focused on the position of the knob & how to stop the player then on whats going on in the game. The movement of the knob, in my opinion, should be much more similar to the pressing of the buttons: instant & controllable without looking at it.

Edit// Maybe the knob thing could be replaced with sort of flashing arrows: when mouse is moved to the right the right arrow on the circle is lit?

Edit//Edit// You actually have something similar to that already: when I hold right mouse button, move the knob all the way to the right and then release the right button, the knob instantly goes to the middle of the circle.