Chess

Chess needs little introduction — it is the strategy game civilizations have argued over for fifteen centuries — but playing it online usually means downloads, accounts and adverts. Here it is just the board: set up, pick a side, and play. Each piece moves in its own way, the goal is to trap the enemy king in checkmate, and everything else is the deep, unforgiving calculation that has kept the game alive for so long. Beginners can play a friend on the same device and learn by doing; anyone wanting a real test can face the computer across easy, medium and hard levels that actually defend, capture and set threats rather than shuffling wood. The value of a game like this is that it rewards you exactly as much as you put in — a five-minute blitz or an hour of deep thought both fit on the same board. It runs instantly in your browser, works with tap or click, and remembers your record. No sign-up, and no clock unless you want one.