Movie like this one

I've been trying to figure out the name of a movie and when I described the plot someone mentioned this one but it's not the same movie. Maybe someone here can help. I can barely remember it, but I think a single mother and her two kids move into a new house. The kids find like a tree fort or club house out back that they start playig in, and it turns out to be evil. I remember at the end they destroy the fort and move away, but the camera pans to the back yard and you see the fort rebuild itself. I cannot remember the name for the life of me.

Can anyone help?

I'm gonna eat your brains and gain your knowledge