Zap Ruder

Zap Ruder is a Zapper test program for Nintendo Entertainment System. It demonstrates the use of the Zapper's photosensor to measure two things: whether it's pointed at light, and if so, how far down the screen it's pointed. The Zapper works only with CRT SDTVs because it relies on the raster-scan behavior of the TVs that were available when the NES was introduced in 1985.

It includes several static test patterns that let the player choose the brightness and color, a clone of 1970s video tennis called ZapPing, and a Zapper-activated music toy.