The Celestial Toyroom was the realm of the Celestial Toymaker. It was filled with toys and traps, and anyone who was caught in there became a plaything of the Toymaker. If the Toymaker ever lost a game, he would have to pay the price by losing his Toyroom, which would disappear. He would therefore have to build another one, although he was alright with this as he got bored with the Toyroom after a while.
The Toyroom included the Trilogic game and TARDIS hopscotch. (DW: The Celestial Toymaker)