I like the character artwork. The old man did look rather creepy. Having an icon for which keys I currently possessed was helpful. Colour-coding the key and door was also useful, as it made it less frustrating to find which key went with which door. An improvement to this could be to have the keys and possibly the doors illuminated to make it easier to find when searching rooms. Most of the time, I had to strafe the room as some of the keys were in the middle of the room instead of the corner.

The house layout was extremely large with rooms of various sizes that were mainly empty with few distinguishing features.  It added to the desolate and isolated atmosphere. However, with the limited range of sight and lack of distinguishing features it was easy to wander in circles for the larger areas. One possible improvement would be to have sections of the house have a theme and unique objects. For example, the area after the red door could be primarily red themed, the area after the green door could be primarily green themed etc. Doors could have a specific set of objects nearby which act as a visual cue for players that are exploring or backtracking. This would also make it easier for the player to create a mental map of the house as they explore.

The old man chasing after you is a good form of pressure on the player, though the AI could be exploited  in larger areas. The sprite could be made a little smaller due to potentially encountering the old man in narrower corridors with dead ends. The camera could also be zoomed out a little more, as when the old man appears directly below or above the character, you will have less time to react than when he appears further to the side. The decision to have the old man visible irrespective of whether the player was illuminating the him was a good choice.