Nucasc

Nucasc may well be one of the strangest reaction games ever written for DOS: by its own description, it does not need a screen at all. It is played with the three indicator lights on your keyboard – Num Lock, Caps Lock and Scroll Lock. The LEDs light up at random and the player has to switch each one off before it goes out by itself, with the reaction window shrinking all the time.

The game was released in 2000 by a group called Team20000 as freeware, the typical route of the Finnish home-computer scene, whose inventive oddities international retro sites tend to miss. Turning three half-forgotten keyboard LEDs into a game display is exactly the kind of programmer humour this scene lived on. You can play it right in your browser on OldGame.cz.