Castle Grex is the lair of King Grex in the Goop series. It is an enormous black castle on an island surrounded by a lake full of lava, with a giant bust of Grex hanging above the gate. It is an enormous castle, featuring a giant engine room and a dungeon filled with ghosts.
Castle Grex contains the following five levels:
|Castle Climb||Basic Level|
|Evil Engine||Basic Level|
|Haunted Dungeon||Basic Level|
|Crumbling Keep||Draclo Level|
|King Grex's Throne||Boss (King Grex)|