Just received my latest robot called Super Fighter, already assembled which is a change for me. I was attracted to this robot as it had a reasonable price, it looked good, it was supposed to walk (which it does - sort of), fire a 'laser', speak and most importantly, fires foam disks out the front.
It is quite an interesting design as most parts are independent of all others. The laser arm contains it's own motor and LED, the two legs have a motor in each foot, the head just contains LEDs and the infrared communications diodes and the foam disk mechanism fits into the chest. It would be relatively easy to add a motor to the second arm as this is not currently motorised, as well as adding sensors and what-knots to the head.
I have already disassembled it and it looks relatively easy to replace the existing controller board with an Arduino or similar. The supplied controller looks like it is some sort of custom single chip microprocessor and I doubt it could be reprogrammed. Most of the motors and LEDs seem to be driven directly from this custom PCB so if replaced it would be necessary to provide H bridge drivers or similar for three DC motors (two feet and one arm), plus transistors to drive the two motors used in the foam disk firing mechanism - these only rotate in one direction so do not need H bridge drivers.
There is some spare room inside the chest cavity for other sensors and radio communications. The current remote control system uses infrared. It might be necessary to remove the foam disk firing mechanism if more space were needed.
I wonder if I could use this for an entry into the Month of Robots competition?