Once you get rid of the permanent magnets though you'd need to power the pucks somehow. With permanent magnets you don't need any kind of active element on the pucks for movement alone.
You could let the pucks make contact with the PCB, and power them like that. If the pucks are pulled towards the PCB, then it is easy to let them make contact.
That would cause the whole thing to wear out in no time. I don't think any contact scheme would work for this kind of application you'd get all of the headaches of motors with brushes but on a tiny scale. Spark erosion would destroy the traces. Part of the elegance of this design is that it is non-contact.
You could power inductively, perhaps. So create a fluctuating magnetic field to deliver power to a coil (which is on the puck), then let a microprocessor on the puck control the flow of current to different coils (also on the puck) which are then pulled towards permanent magnets in the PCB.
Hm. You got me thinking about this: another layer below that can send a 'charge' pulse to a coil on the puck to charge a super cap. Bonus points if you can turn that into a levitation mechanism.
This is along the lines of what I was thinking initially but more by reacting to the instantaneous current induced in the coil rather than a charge/discharge action.
Where the ring launcher works by counter emf that evolves in the conductor, a tuned emf (like for RFID chips) could be made with specific properties. Eg. it might only respond to certain frequency bands and possibly (?) allow for both repulsive and attractive forces by either maintaining or inverting the exciter phase in the board.
You could let a microcontroller on the puck control the allowed currents. If you do this sufficiently fast, you can multiplex over different pucks on the board.
Creating a tuned oscillator could be interesting too, but could also turn out to be too heavy, in terms of component weight.
