Marcianitos (Space Invaders) is the classic arcade game originally released in 1978. The player controls a laser cannon by moving it horizontally across the bottom of the screen and firing at descending aliens. Defeating the aliens brings another wave that is more difficult.
The aliens attempt to destroy the cannon by firing at it while they approach the bottom of the screen. If they reach the bottom, the alien invasion is successful and the game ends. Gameplay is endless, so once you clear all enemies, new ones will appear. Good luck!