Space Invaders

Space Invaders is a 1980 Atari 2600 game from Atari, Inc., originally released in arcades in 1978, catalogued here for 4 defining game mechanics.

Atari 26001980Originally Arcade 1978Complexity 18/1002D SidePopular

Space Invaders is a 1980 fixed shooter developed and published by Atari, Inc. for the Atari 2600, a port of Taito's 1978 arcade game. (via Wikipedia)

The genre Space Invaders helped define

Fixed shooter. The home port that became the VCS's killer app and cemented the fixed-shooter template.

Contact DamageCombatTouching an enemy or environmental hazard deals damage to the player without any explicit attack trigger from either party.
Projectile SystemCombatPrimary player-versus-enemy interaction is firing and/or dodging discrete moving objects.
Lives SystemResourcePlayer has a finite number of attempts; losing all lives resets progress to a defined point or ends the game.
Wave SpawningSimulationEnemies appear in scripted or procedural groups at intervals; surviving each wave is the primary challenge loop.

Each mechanic links to how to build it in Godot, with the retro games that share it.