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.
Study the source
Source-available (No formal license (community source)). Browsable, commented 6809 assembly source for the Vectrex Mine Storm built-in game plus an as09 assembler build environment. https://github.com/mikepea/vectrex-minestorm