At the title screen press c-left, L, c-right, R, Z. A sound will confirm a correct code entry. The new rings include Graveyard, Spaceship, Circus, Hive, Turbo, Wunderland, Boudoir, Hall of Mirrors, Rec Room (this is my favorite! you get to wrestle on a pool table!), Psychodelic, Disco, Jungle, 1984, Quark, and Texas.