Hi. I tested your game for about 45 minutes to an hour, up to the statue room with the priestess, demon, and knight puzzle. I'll be cash: for a first game, it's good work, I even find it better than the majority of other games of the same genre. The atmosphere is there and we can see that you worked on the lights and shadows, it's clean.
That said, I have a few remarks to help you if you want to develop this over the long term. First off, Arthur runs way too fast, he's like an electric battery, it breaks the mysterious atmosphere, you should slow down his movement speed. Regarding the narration, it's still a bit empty, we don't know much about him other than that he's lost, it would be good to add a bit of context so we can get attached to the character.
Your puzzles are well-made, they are nice and I enjoyed solving them, but be lucid: it's twisted and some players will struggle or give up. I noticed that you already added some hints (like those regarding "CONTE"), but they are a bit hidden. If you want the game to be more accessible, try to make them a bit more visible or add one or two more.
On the decor, the 100% RTP side makes it a bit too "square", try to make it a bit more organic. Finally, the music is a bit redundant when you've been thinking for a long time, changing the track according to the floors would be a real plus. It's not meant to be mean, it's just my honest opinion to help you move forward. The game isn't bad at all, it's a very good start, keep it up.