Tempest (1981)

Tempest is an arcade game by Atari Inc., originally designed and programmed by David Theurer. Released in October, 1981, it was fairly popular and had several ports and sequels. The game is also notable for being the first video game with a selectable level of difficulty (determined by the initial starting level). The game is a tube shooter, a type of shoot 'em up where the environment is fixed and viewed from a three-dimensional perspective. Source: Wikipedia, "Tempest (arcade game)," available under the CC-BY-SA License.