Josh, as the readme states, the levels included are some particularly tough ones. No, seriously, it says: "There are six levels available, and we picked out some particularly tough ones."
That said, I've completed all but #5. I only got one wrench though and now I'm wondering what those are about.
Tried the demo. Most old-school arcade games start out a little less challenging. Warm us up a bit and show us the potential problems before diving us into a jump-for-your-life pattern.
PS Congrats on the funding!
Rest. We look forward to your demo when it is time and ready.