Minor spoiler ahead. It seems this entry of the dystopian variety may have gotten some inspiration from one of my favorite episodes of the original Star Trek series in my opinion. Much like this movie, the episode titled "Miri" was about a virus that became deadly when the infected reached puberty, hence the lack of any adults existing in this world. So you take that episode and extend it by an additional 20 minutes and you have this movie. The actors all did well in their parts presenting the story and the environment was well established with the help of an abandoned amusement park. It's a decent effort but if you want essentially the same story handled in a more compact and efficient way, I recommend the Star Trek version.