Sounds like you're on track. You'll want to develop the jar of acid, since it is needed for the other three endings. Not sure how much you've done, but you'll need to discover the water source (and block it) as well as explore the dark parts of the cave.
If I had to guess, it's probably the waiting mechanic that's getting you stuck. For example, waiting in the dark for your eyes to adjust so you can move forward. It takes a few seconds of not clicking anything. You'll need to do something similar when searching for the water source.
Let me know if you need more specific hints.