The concept is original and farily well-implemented, I love how the mouse's speed determines the "strength" of your movement/turn, it feels like you're physically struggling to move. One nitpick that I have is that having the mouse movements be "up = forward" and "down = backward" can get a bit confusing when you have to move east or west. It would be more intuitive and immersive if the mouse's "forward" and "backward" were relative to the direction in which the player character is looking at.