I think where they went wrong
I'll start off by saying I've played all the games and I quite enjoyed the movie.
I think though where they went wrong was assuming all people going to see this have played the games. Yea that was their target audience but the constant in seeing from the critics is that they don't get it or there are too many unanswered questions. To me, instead of making the movie less than 2 hours, maybe they should have added just a bit of time explaining things a bit more for the non creeders.