First playthrough:
I got stuck in level 6 with not enough keys because...
Spoiler
Even though the quest was frustrating at some points, it was good enough that I wanted to try completing this quest so I started over... FROM THE BEGINNING.
Second playthrough:
Using my experience from the first playthrough, I successfully navigated level 6. However, due to the bug bigboylink described, I got stuck in level 8. I was NOT going to restart again.
-I watched a playthrough where there was a key shop hidden in the cliff before level 5, but it was not there in my version
-No way to activate the cheats to give myself an extra key
If I would have been able to finish the quest on the second playthrough, I probably would have rated the quest 3 stars. There are a lot of redeeming qualities as highlighted by the other reviews, but to get stuck (not "oh what do I need to do... let me think about it" kind of stuck but GAME ENDING stuck) TWICE, the quest is unplayable for me. Yes, I got 9 hours out of it, but I consider an unplayable quest one where you can't get from the beginning to the end.