A fast-moving holographic strategy game played with finger controls, at which the Zakdorn tactician Sirna Kolrami was a grand master and Data forced a famous stalemate.
Strategema appears in the episode Peak Performance. Two players wearing metal controls on their fingers manoeuvre coloured shapes on a holographic grid, trying to take territory from each other.
Sirna Kolrami, sent to observe a Starfleet battle exercise, is a third-level grand master and condescending about it. Riker plays him for the honour of it and loses quickly. Data is then persuaded to try, on the theory that an android cannot be beaten, and loses too. Shaken, he withdraws from duty to look for a fault in himself.
In the rematch Data stops trying to win. He passes up chances to advance and plays only to keep the game level, so it goes on and on until Kolrami storms away in fury.