Gnomes are matched by color horizontally or vertically. They can march in a row horizontally, or you may select one to go up the stairs to a row above or below it diagonally. A few more gnomes enter the cave every turn.
Some gnomes are magical. The Light Side gnomes can change the gnomes colors to match, two spaces above it. The Dark Side gnomes change the color of all the gnomes below it. Each of the magical gnomes vanishes after they cast their spell. They may not move up or down the stairs, but they may march along the row horizontally.
The game is over when the cave is all filled up, and all the gnomes need to leave because their union has strict rules about overcrowded workplaces, and do not believe in simple accidents.
So good luck, foreman!
Match gnomes tic tac toe style by walking them along their row or up the stairs.