Peg solitaire, Solo Noble, Senku or Brainvita is a board game involving movement of pegs on a board with holes. Some sets use marbles in a board with indentations and digital games as this one use colors circles. A valid move is to jump a peg orthogonally over an adjacent peg into a hole two positions away and then to remove the jumped peg. The objective is to empty the entire board except for a solitary peg in the central hole. With 75 levels this is the perfect game for your brain.