What do I need to play?

[AnyOldName3]

The sensor bar is just a stick with 6 or 10 IR LEDs inside and there is is an IR camera in the end of the wiimote which sees the groups of 3 or 5 at each end as two points and from that it can calculate distance from the bar, rotation relative to the bar and what angle the bar is at relative to itself.

So basically all you need to give the bar is 7.5 to 12V (the power of the output on the back of the Wii) unless you change the resistors for weaker ones so you can run it off 5V from a USB 2.0 lead. Often wireless bars eat batteries really quickly, so these are sometimes converted to run off USB, and usually the resistors don't need to be changed, as a four battery wireless bar needs about 6V, which is fairly close to 5V from USB.