Yeah unfortunately Blomkamp was in the running to be chosen to direct Halo movie and was working rough drafts and concept art for a while before Microsoft canceled the entire project. I believe he did make a short film for their ads (Halo: Landfall (2007)). I know that they chose him on the strength of a short film (Alive in Joburg (2005)) whose plot eventually went on to be the seedlings of District 9 which would come out in 2009.

Once you recognize that they were trying to salvage a lot of the work they did in preparation for Halo, suddenly it becomes a little more obvious why it was an action movie instead of something more grounded with the same ideas. To me the alien weapon designs seemed very Halo style.

And I agree entirely, I think the film was held back by trying to be an action movie and social commentary at the same time.