#handheld

Lights Out (1995): Press a Button and Its Neighbours Flip. Linear Algebra Sat Under Those 25 Buttons

Tiger Electronics' 1995 handheld Lights Out is a game of 25 buttons where each press flips its neighbours. Beneath it lies linear algebra over 0 and 1: only a quarter of layouts are solvable, and 15 presses is the worst case. This article follows only verified facts, from the earlier Merlin (1978) and XL-25 (1983) to Sutner's 1989 paper and research that continues today.