I just finished my first playthrough of Jets 'n Guns Gold in probably 6 years, and listening to it with fresh ears, I had a 'holy shit, this is a shmup soundtrack?' moment. The game's OST was done by a band described as "SID Metal", for using an electronic organ with a Commodore 64's sound chip (the Sound Interface Device, or SID) implanted in it. So those beeps and boops aren't scripted, but a live human playing a physical instrument. The band itself, Machinae Supremacy, is a kind of edgy anarchist "smash the system" 80s/90s punk group, but they fucking nailed this OST. They have a big history of taking inspiration from classic games in even their studio album work.
The game itself is a Western-style shmup, so lots of twitch-reflex gameplay instead of Eastern-style danmaku pattern memorization. An absolutely ridiculous number of weapons, too.
Embedded is the game's entire OST. Suggested tracks/personal favorites are:
00:00 - The main title theme.
15:57 - Lava Trouble Bubble
40:47 - Death From Above
1:03:05- Mostly Dark Universe
What other really unique soundtracks are out there? Not just 'good', but strange.