For the most part, this entry is simple but effective.
Presentation-wise, I have nothing but good things to say about it. The 2D shadows are well done and I especially appreciate the way the lights disappear when the source is blocked by an object. The music is great as well.
I think the game could use a little more polish. Puzzles involving buttons and switches start to run into issues and the collision detection on multiple graves near each other can get buggy, which is a significant issue when these graves are the only thing between you and a spike floor.
I don’t think it would be a stretch to say this is a viable commercial concept, and putting aside the bugs I think you’ve done a great job creating a minimum viable product.