Thanks for the detailed feedback! You make a lot of fair critiques, some I expect and some I can learn from for sure! :) I made a decision early to not let the player backtrack, strictly for the purpose of the Game Jam to 1)make it a straightforward game and 2)limit my workload a bit because I would've gone back and created all new dialogue after each event and that would equal a lot of development time.
Very true about players feeling anxious about missing things and not being able to go back (I feel that in games too) and I would love to go back eventually and make backtracking a reality (and more openness as well wouldn't hurt). As for star fragments, there are 5 total, one in each area, and the energy for the crystal (4 total) is all located inside the dungeon itself.
Glad to hear you enjoyed it, because to me that's the most important thing I want out of making games. :) Still have a lot I can improve on but that will come in time.