8-bit music was popularised by 80s game consoles, such as the Commodore 64, Sega’s SG-1000 and Nintendo’s classic NES. It was mostly used due to its incredibly small file size as at the time. The consoles the games ran on had very limited capacity and its size was due to the simple synthetic sound it produced. Soundtracks are developed using digital waveforms but 8-bit has a distinct sound because of how simplified it is and how the limitations of 8-bit differ from 16 or 24 bit sounds.
The higher the bits, the closer to the original waveform the audio will sound.
8-bit sounds simple, but that’s what makes it so catchy. I carried out a small experiment with my dad, who I know played games on the Commodore 64 and NES as a kid and plays games like ARK and Satisfactory now. I played three soundtracks from games he mentioned he played as a kid and three from the types of games he plays now and he could hum the majority of them from memory but could only remember main melodies from modern games.
It’s also likely why soundtracks from games like Tetris, Pac Man and Donkey Kong are still well known to younger generations today. Some have been reused for multiple games but altered and updated over time, some have been used as ringtones as they were that catchy.
24-bit audio is the standard of what we use today. It’s considered high definition but has a much larger file size and no longer has the distinct retro sound.