This is a simple console-based C++ game inspired by the game Defender, which was released in 1981 for various platforms, including the Atari 2600, Commodore 64, IBM PC and arcades. It's a side-scroller shooter game where you control a spaceship and must defeat all enemies in the level.
Defender was inspired by other space-related games of its time, such as Space Invaders and Asteroids, and made the side-scroller shoot 'em up genre popular.