I've never played the early-days Sega Genesis title Ecco the Dolphin, though it's certainly amassed its fair share of retro enthusiasm, and, for a while anyhow, seemed to be on-track for a reboot. It's a game about a dolphin that sings at crystals and fights aliens and does cool acrobatics, from what I understand.
It is also a game with a soundtrack that is legitimately sick as fuck. I was put onto it earlier this week by a friend, and, I think you will agree, it's a revelation—a transportive soundscape of sweeping, droning sci-fi synths and 8-bit audio softened into dreamy electro. It befits a game about a chill time-traveling dolphin.
There's some confusion it seems about who actually composed this. The description for the YouTube track above identifies it as the work of mainstream-y game music composer Spencer Nilsen, but a commenter notes that Nilsen composed only the CD re-release of the game. The Wikipedia entry for the game credits the music on the cartridge version to Csaba Gigor and Gábor Foltán, whom I can find basically nothing about. Good work, nonetheless.