Saw (2004) -

The film's ending remains one of the most iconic "gut-punches" in cinema history. It worked because it subverted a classic trope: the killer wasn't a shadow in the corner; he was the in the center of the room the entire time. Critics at the time, like those at Rotten Tomatoes , noted its nihilistic streak, but audiences turned it into a massive hit, grossing over $100 million worldwide. Saw (2004) - IMDb

The entire movie was filmed in just 18 days , with the central bathroom scenes taking only six days. Saw (2004)

It was shot for roughly $700,000–$1.2 million . The film's ending remains one of the most