Chex Quest, made by Digital Café, is a total conversion of The Ultimate DooM. It was released in boxes of Chex Cereal in 1996, becoming the first game to be included in a cereal box. When it was released, it increased sales by over 200%. It then went on to win both the Golden Reggie Award for Promotional Achievement, and the Silver EFFIE Award for Advertising Effectiveness.
The opening video shown when running the original .EXE