I had the same issue being unable to open the final chest after killing the spider. But I enjoyed my time playing the game otherwise. 

Momma Gob the goat. Love that this was made in GB Studio, it really made the game feel like a gameboy game! Grat job, I enjoyed the story and the color palette!

Much of the same as other folks here. I also had an issue with the chest at the end, I think if you pass by the spider without killing it first it just completely breaks your ability to open it. It was a bit confusing at times figuring out how to do things, like I spent a few minutes trying to figure out how I can use the torch before I recognized the unlit torch I could interact with. I got very confused in the riddle cave (Snake Eater reference is very cheeky, I like it) where I solved the riddle, but I didn't realize the chest down below so I wasn't sure what the result was. I think it was mostly a lack of contrast in the graphics that might have been the problem there. The pathing is a little bit awkward too, a lot of times I'd walk against the wall and be a bit confused that I couldn't walk along it.

Regardless, this has a nice progression for a complete game, and the narrative is very sweet. Great job!