How many legs does R2D2 have, 2 or 3 ? What is best ? Try it for your self by building a robot that can run on 2 or 3 wheels. This is the software for running and controlling such a robot based on the lego mindstorm nxt kit.
When starting the app you are presented with three options, Drive, Balance and Advanced. The drive option works for any kind of nxt based robot with motors connected to the B and C port. The only requirement is that the nxt is on. The robot is controlled by tilting the android device.
The other options require a self blancing robot. Building instructions for a R2D2 like self balancing robot is posted at http://www.olaochelliot.com/page6.html Also the software for a self balancing robot with 2 wheels can be found there. The advanced option can be used to control a self balancing robot with an arm. Instructions for a R2D2 robot with ar is posted at http://www.olaochelliot.com/page7.html