Tetris

The arcade Tetris is the only version of the game that turned it into a duel. Alexey Pajitnov's falling-block puzzle was licensed to Atari Games for the coin-op market, and Atari's answer to the obvious question - what does an arcade machine add to a game people already own? - was a second player.

Two boards, two players, one cabinet, and every line you clear is added to the bottom of your opponent's stack. That single change turns a solitary endurance test into a race with a visible opponent, and it forces a completely different set of decisions: clearing four rows at once (a Tetris) sends four garbage rows across, so the game rewards holding a well rather than cleaning up constantly. The pieces follow the original rotation rules rather than the modern ones, there is no hold slot and no hard drop, and the speed curve is deliberately steep. It is the version that predates the standard everyone now expects, and playing it makes the differences obvious.

• ▸Two-player head-to-head with garbage rows sent to the opponent
• ▸Clearing four rows at once sends four rows across
• ▸Original rotation rules with no hold slot and no hard drop
• ▸A deliberately steep speed curve tuned for coin drop