Also, two of the characters are extremely neglected and their subplots are never carried through to fruition.
At first this seems to have a healing effect, but slowly we see that all is not what it seems to be.
One of Chatroom's strangest failures is that it doesn't seem able to integrate and weave together main-plots with sub-plots and character development, instead assigning blocks of time and space to deal with each separately.
It makes unsatisfying story-telling; not all that much interaction takes place between the main characters, their lives mostly just play out independently, without much consequence except to show how inexplicably malicious the main character is.
The movie goes back and forth between "real life" (the outside world) and internet life (the conversations and chats of the protagonists, here represented into a physical reality, so as not to spend an hour and 46 minutes filming youth typing on a keyboard).
It is not a horror movie, but rather a good psychological thriller, with the story of a disturbed teen who tries to alleviate his own misery by making others miserable.