Was totally lost playing this. I guess your lack of time was definitely a factor. The fog of war effect was good.

As you said, not really a game, and the collisions were messed up indeed. I liked the viewport effect though and it's a shame that you didn't do more with it.

The viewport was enough to get me thinking about possibilities, so that's might be a good sign. I know plenty of games have used the limited sight mechanic in dark areas, but it is usually either a circle around the player, or a cone starting at the player's location. It could be an interesting deviation to have the visible area be a region around the look-at target (probably controlled by the mouse position), and the actual area around the player could be blacked out, as in your prototype. That might make it more intense, as enemies could quite easily sneak up behind you while you're distracted with some action elsewhere.

Actual flashlight physics could be used to light up the ground with an ellipse where the player is looking, and also light up the front of any enemies or other objects between the player and the look-at location, so that enemies couldn't approach from the front, while still keeping plenty of suspense due to risk of attack from behind.