Vertically-scrolling, single-player tank shooter a la Combat. Your tank moves and shoots independently in 8 directions as you destroy rotating enemy turrets and trudge over difficult terrain. The goal is to move onto the silos, which triggers a launch sequence in which one has 30 seconds to input a 3-letter code or lose the Earth to a graphically and musically impressive nuclear destruction. Along the way, you can run over icons which look like spools of thread, which will you tell you one of the code letters.
Not much replay value, but the graphics and sound are quite good for the era.