Great work! I really liked how how moody everything became with the lighting.
The level design was good. I never felt stuck and even though I sometimes felt just a bit of lost, it was always possible to find my way again and figure out what to do. If anything it just made things more interesting. I think you did a really good job on making the character slow and the spaces you traverse small. Outside the lighthouse is an exception to this, having to walk around there without actually knowing what to look for was frustrating. Once I got inside though, it was really good. I'm also a huge fan of the ingame text.
Some feedback:
The gameplay does get a bit repetitive. Find locked door, look for key, find key, unlock, repeat. It's a loop, which is a very good start, but it could be made much more interesting if there was more variation. The spooky figure was a great addition that did make things more interesting, the game just needed a lil bit more of that kind of stuff.
All that said, you seem to be at the start of developing games, and having submitted to a jam is an incredible feat in itself. Fantastic work, and keep it up!
Also are you using FL keys?