Atari 2600 - Combat

Possibly my favorite game for the Atari 2600 was Combat.  A two player competitive game.  You could compete against you component with tanks. There were more options as well, such as: tanks with barricades, tanks with more barricades, tanks with bouncing bullets, invisible tanks, biplanes with clouds, biplanes without clouds, bomber and planes, jets with clouds, etc.
Eons later, the Nintendo Wii had a remix of the concept with tank combat on Wii Play, albeit with much better graphics and controls.

One of the best parts of the Atari games were their picturesque manuals. The graphics were so rudimentary, the game left much to the imagination. And the manuals and comic stoked the fires of the mind!