Checkers

Checkers, or draughts, is the diagonal-board classic that people underestimate until the computer quietly dismantles them. Your pieces step one square diagonally forward onto dark squares, you capture by jumping over an opponent's piece to the empty square beyond — chaining more jumps in the same turn whenever you can — and reaching the far row crowns a piece a king that moves and jumps both directions. The rule that shapes real strategy is that captures are forced: if a jump is on offer, you must take it. That sounds like a constraint, but it is actually your sharpest weapon, because you can bait the computer into a mandatory jump that springs open a bigger capture for you. Beyond that, control the centre where pieces have the most influence, hold your back row together early to deny easy kings, and remember the endgame maxim — trade pieces when you are ahead, hoard them when you are behind. Hard looks several moves deep and punishes loose play but stays beatable; Easy forgives more. It plays free in the browser on desktop or phone, with your wins kept between games.