"Um ... So I think it's officially my next film. #alien," he wrote on social media at the time, even sharing some early storyboard art with fans on his Instagram account.
But the film never came to be - veteran director Ridley Scott, who helmed the original 1979 Alien, had re-entered the franchise with 2012's prequel Prometheusand decided to follow that up with another Alien film.
In a new interview with Funhaus, Blomkamp gave some tantalising insight into what might have been in his vision of Alien - including a continuation of Signourney Weaver's iconic Ellen Ripley character.
"I met Sigourney on Chappie and I had a different idea for an Alien film I wanted to make. So I had this idea for a story set in the world of those two first films that was not a continuation of James Cameron's," Blomkamp said (Cameron directed the 1986 sequel Aliens, considered by many to be the high point of the franchise).
"It was just in the world of it and it had a totally different character that was the lead character, because my assumption was that Sigourney would just never make another one. I told her about it on Chappie and she was like 'No, no, no! I actually would make another one because I felt like Ripley's story didn't end correctly.'"
The last that viewers had seen Ripley was in 1997's Alien: Resurrection, a so-so entry into the franchise that earned mixed reviews from critics and audiences alike.
But with Weaver indicating she'd like to revisit the character, Blomkamp got to work. He worked on a script for "about a year", enlisting a concept artist to work on the look so key to the success of the Alien franchise.
"We put together essentially a script and all the artwork and that's what I went to 20th Century Fox with. They seemed really into it and Ridley [Scott] came on as producer and then it just unravelled."
Blomkamp chose his words carefully as he explained how Ridley Scott's involvement saw his vision for an Alien reboot "collapse".
"It's very difficult to speak about on several levels because Ridley created Alien. It was something that inspired me deeply. I got into film because of it," he said.
"Everything that happened with my script and with the way the film collapsed - it's hard to talk about it without it seeming like I'm bashing him which is like one of my idols to get into film. It's a super strange psychological place but films go down in Hollywood all the time. That's just essentially, I think, what happened and it sucks for me.
"It's not that it sucks for Sigourney, it's not going to make any difference to her, but I think she really did like the story because it allowed Ripley to ... it really felt like a cool third film."
Still, at least we got Alien: Covenant , which gave us ... a robot Michael Fassbender playing the recorder. Gah.