Symphony Quest website announces the full release of this musical action/RPG from Toadstool Games. Here's what this is all about:

Symphony Quest is a single-player, and cooperative multiplayer action role-playing game for the PC. With the rise of a Goblin menace, civilisation has collapsed, and you must fight to ensure the survival of humanity. Nearly too late have humans discovered the greatest weakness of their new foes; Music.

The ‘Symphony’ is the magical, musical technology used by mankind to fight against goblins, and the hostile environment in the shattered remains of earth, now known by most as ‘Dischord’. The player controls ‘Symphony’ with an 8-key layout on the keyboard, corresponding to a full octave. Specific, melodic combinations activate abilities that can be used to defeat enemies, assist allies, and solve puzzles.