Alternative Idea

And yes, its realistic.

Here are some quick notes I made:

On the computer playing games at night. There's a power cut.  Goes to phone and continues to talk with friends. Conversation steers towards “what if its someone trying to break in” and other scary things. Phone battery begins to die so he goes with a small torch to light a candle. Strange noises come from outside. They investigate and a figure can be seen in the garden. They investigate slowly. The garden door slams shut and a figure can be seen entering the house. They are shocked and go to call the police. The phone dies. The original figure is no longer there and they look around in the garden to try and find them. As they turn around, the figure is standing directly behind them and they move quickly towards the character. The intro ends.