Cool little concept! Love the one-screen flavour and the idea of having to slowly climb up through the castle's rooms.
In terms of critique, it could have used a bit more visual highlighting (torches, glowing ladders etc.) of areas since I found myself often lost looking for obscured ladders / platforms in the dark. Was also a bit confused to discover that jumping only unlocked when getting into one specific room. The dragon fire is brutual as well hahaha - maybe more of a 'damage-over-time and you can put yourself out if you get out in time' model would be a bit more forgiving (unless you were going for the hardcore permadeath kinda vibe)!
Altogether a solid submission - great work!