Shane Carruth's follow-up to Primer, titled Upstream Color, arrived nearly nine years later, and as with his previous work, he took on numerous responsibilities in its creation – serving as producer (among others), director, writer, actor (among several), music director, cinematographer, and editor. The film was produced for a remarkably small sum of $50,000; it’s truly impressive how economical they were. While the narrative isn't as complex as Primer, which explored time travel themes, it also doesn't present itself in a simple way. It touches on unusual occurrences and can be challenging to grasp at certain points. If you haven’t seen it yet, I suggest checking it out.

Source on TMDB