This is a pretty decent base for what could be a good game. I like the idea of seeking out artifacts in a haunted mansion, but this is pretty simplistic.
First things first. The art style in this game is pretty simple, and I think that's due to the overall low resolution of the sprites. I think that the overall atmosphere could be enhanced with some bigger sprites with smoother animations. It would also help to perhaps place smaller details like ruined objects or rotting floorboards randomly scattered throughout the level to help make the entire maze feel less same-y. I would also advise against meshing larger sprites with smaller ones. The variance in pixel size can be jarring and generally looks off.
Secondly, there's the gameplay. For the most part, it just boils down to really zoomed in pac man. The idea of ghosts that you can only see in a flash of light is really cool and helps keep the player tense and on their toes, but having the ghost flash up every single time the player comes near pretty much removes the tension seeing as the player knows that they'll be alerted whenever an enemy is nearby. I think it would be better to have a device of some kind that the player can manually activate to flash their surroundings to check for ghosts, perhaps with some kind of short cooldown so that it's not very spammable.
Third, the level design. The constant narrow corridors make the entire experience feel very claustrophobic, which is a good thing for a horror game, but it's not terribly engaging. When playing your game, I never really felt like I was trapped inside a haunted manor. It was closer to haunted maze or cave that happened to be lined with wood for whatever reason. In order to better achieve the feeling of being trapped in a manor, I would recommend making a series of modular rooms that randomly rearrange themselves with every playthrough. Think similar to most rogue-likes.
Those are all the major things that I would recommend to improve your game. As for smaller things, I think it would be beneficial to have some sort of way to distract or repel the ghosts because when multiple of them gang up on you, it makes for an unfair escape. I also think having a greater incentive to actually collect the artifacts would be nice, as well as a meter or some sort of indicator telling you how many of them are left so that players who've already collected them all don't have to wander around wondering if they should head to the exit or keep searching.