Watched last night...Paranormal Activity 3.
Although starting in the modern day, this quickly jumps back to 1988 (although you wouldn't necessarily know this if it wasn't stated on screen - the film doesn't go a particularly long way to making this feel like a period piece) and serves as a prequel to the first two films in the trilogy.
It is somewhat more polished than the original, which is not surprising as this one was made on a budget of $5m vs the twenty quid that the first one had, but still goes easy on the CGI and relies more on practical FX which is pleasing. A piece of ingenuity gets around the static fixed camera approach of the original, and there are a couple of great set piece scares. The two child leads manage that trickiest of things in horror films of not being extremely annoying, and the adult cast all look suitably terrified when required.
As a prequel, this serves to set up the lore seen in the first two films, although I"m not sure to what extent the whole arc was thought about prior to the wild success of the original film. Nonetheless, there is some decent backstory including the obligatory scene of reading a book on demons and witchcraft from the library. 7/10