The Plinth requires 3x AA batteries to play the game; these are not supplied in the core games sold at most stores.
You'll need to unscrew the battery container on the underside of the Plinth to insert the batteries:
Please see the the paper instructions pamphlet inside the box, quick start section 2, if you require further instructions on doing this. (A PDF copy of these instructions is available here).
We recommend only using good quality Alkaline (non-rechargeable) or Ni-MH (rechargeable) batteries with the game. Depending on the type of batteries you use the expected battery-life should be between 30-40hrs of constant gameplay.