NFL Challenge was a computer game, released in 1985 by XOR Software. It was notable for being one of the stronger football simulations of its time, with statistical models to not only the NFL season, but also the outcome of a single football game. Being one of the first football games for the PC it is still considered one of the best requiring 10 man-years to make and over 30,000 lines of code. Source: Wikipedia, "NFL Challenge", available under the CC-BY-SA License.