This is the kind of things that interest me the most.
My ideal simulator is made by two concentric spheres.
The inner sphere is where the sim guy sit and is moved by wheels attached to the outer sphere in contach with the inner sphere. The wheel can rotate in Z axis and also spin. The spinning of the wheel by a high friction cause the inner wheel to spin. I have tons of ideas like this. The force tho they should generete is massive but the idea is that the inner sphere is free to rotate in 3 dimension and change direction very fast. There a lot of technical tricks to achieve this, should not even be hard to do, but the power that such a device would drain in terms of currents and Watt is too much, and a normal house should not be able to feed the Watt to this device. Also this would not give a real G feeling but more an orientation feeling.