The rook and the bishop
The rook
Straight along its rank or file, as far as it likes. Tap the rook, then a dot.
The bishop
Diagonally, as far as it likes. It stays on its own colour all game.
Pieces in the way
Neither can jump. It stops before its own piece, or takes a black one.
Moving onto a square held by an enemy piece captures it: the piece comes off the board and yours takes its place. You can never land on your own piece.
Each side has one light-squared bishop and one dark-squared bishop. Between them they can reach every square.