It's a different medium, so I knew it couldn't sustain the terror of the games non-stop. In film you have to have room for exposition, character development, etc, so it's a lot harder to keep the audience in a state of continual tension like the games do. And I imagine a major movie studio probably would be nervous about that anyway as it makes the film less "marketable." Honestly, I'm impressed they were able to make it as scary as they did.