Brain games ask for a small, clear effort: fit shapes into a grid, fill a sudoku row, spot two matching tiles, or find the word hiding in a letter soup. Nothing needs reflexes, and you can stop between two moves. That is exactly why they work on the metro.
Block Blast sets the tone: place pieces on an 8x8 grid, clear lines, keep the board open. Sudoku rewards patience more than speed, and Nonogram turns numbers into a picture one square at a time. If you prefer cards, Solitaire: The Eternal Deck and the mahjong tables give the same quiet thinking with a different rhythm.
Start with one game, play three rounds, and see which kind of thinking you enjoy most.