ZeroRanger is a project that floored me when I first played it. It stands out aesthetically, and it's gameplay loop is built around replayability with a plot that reinforces the want to repeat and eventually succeed. It's a lightning-in-a-bottle indie project that deserves to be experienced by everyone, and GOG is a great platform to ensure it'll live on.
I have a sneaking suspicion that a lot of indie shmups that have come out after ZeroRanger are inspired by it. Art that impactful deserves to last.