Wow there's a lot to do in this game! I just got the Cliffgrippers and found the Sound of Cat's Feet that I'd been curious about! I was actually clicking a lot at first and then realized I could hold the button down, which ended up being important, haha.
The feeling of progression is really really good. Upgrades definitely make a huge difference! I'll definitely be back to pack up and head out into the strange cave. :)