Here are my thoughts on this story, if you haven't finished the story yet and wish to, you should probably skip reading this until you have played it through.
-POSSIBLY SPOILY REVIEW- (Does this forum have spoiler tags?)
Spoiler below!
I just played through the story, and overall I really enjoyed it. The cell puzzle was a bit difficult to figure out, and as a previous poster mentioned I was distracted by the table with items on it, I figured I could move it closer and grab the items and they were needed.
Well I grabbed the items but they weren't useful! I eventually got out, though.
Overall the atmosphere was very creepy and scary, personally I didn't find the jump scares to be too effective, but the monster encounters were quite good. Saying that, the dropping helmet, and the falling vase, and doors throwing themselves open add to the atmosphere though, even if it didn't startle me much.
I did also notice flickering textures which I assume is from overlapping pieces, which is ignorable to some degree, in any case I'm sure you will stop that from happening with practice and tweaking.
This definitely gave me a glance into what future custom stories may be like, the toolset definably seems that it can be used to produce quality stories with the same great atmosphere as the packaged game.. Now to wait for H.P Lovecraft's Mountains of Madness to be created with the toolset!