Which movie do you feel has the most wasted potential?

There was this alien invasion B-movie like 10 years or so ago that I don’t remember the title of. But it was your typical main character and a couple of friends trying to find a way out of the city. Very generic. Then in the last 10-15 mins of the movie, he gets abducted and it gets far more interesting. But it ends there as a cliffhanger. I would’ve loved to see a version where that happens in the middle of the movie instead and we see more.