“I will NOT swamp my magic sword for your spiky club thing, so just stop asking.”

THQ today announced that it will publish two original downloadable properties from Psychonauts and Brutal Legend developer Double Fine Productions. The first fruit of the partnership will be Costume Quest, a comedic action RPG. Though details are scarce, it appears that players will don makeshift costumes and participate in traditional Halloween activities like suddenly being transformed into colossal robots and stomping evil monsters.

Costume Quest is the brainchild of Tasha Harris, who was probably best known for Tasha’s Donkey Kat Bros. Chronicles (not a made-up title) before finding a wider audience as lead animator on Brutal Legend.

As reported by Joystiq, Double Fine is working on at least four separate projects. Virtually nothing is known of the other three games and it remains unclear which of them will constitute the second leg of the THQ deal.

Costume Quest is due for release on Xbox Live Arcade and PlayStation Network in early 2011.