What sets a HOTAS apart from an "average joystick" is that is consists of two modules that are in some way physically connected:
The "stick" and the "throttle".
Each requires the use of one hand for operation, hence the name.
The only ways of further upgrading a HOTAS system are adding control pedals and/or a head-mounted motion-tracking system.
To date the most complete and critically acclaimed models are for a realistic(flight-sim) approach Thrustmaster's Cougar HOTAS and for a sci-fi(MechWarrior/Space-sim) approach Saitek's X52.