This one may be my favourite - a contender with 8-Bit. Suitably difficult, but solvable with perseverance rather than with hints or specialized knowledge. Although I will say that the ones where I’m researching and learning about different encryption methods are always a fun exercise!

Darn, had to read hint to figure out the purple triangle. I was way off, I thought it was +-3 letters depending on something I hadn't figured out yet.

This one was easier than the previous 6 Theorems for me. I like this style of puzzle. The tricky part was finding the purple, which made my answer weird. Once I figured it out, it made it very easy

This is a great puzzle.

In general, easy or hard might depend on your background, or just what paths you tried yourself.

I don't mind using hints if I have no idea how to proceed, but it's nice to try and solve it yourself.

I love this puzzle

Knowing a bit about circuitry and being a political science major, once I got the first letter (R), I knew. Very clever M, very clever indeed.

Okay, I see what the purple inverter does. Explains why the binary solution only works in one spot by coincidence.

I find that whether these puzzles are easy or hard must be highly subjective. Some of the easier I have a heck of a time figuring out what M's train of thought is, some of these harder ones, I can see it almost immediately. I must say, I am still trying to figure out exactly how the purple symbol works. It seems to fit the binary thing, at times, but its function doesn't seem to be as simple as the other symbols. I'll keep working on that. But I didn't need it work out the answer in a trice. I _like_ this kind of puzzle!

And, like ReverendTed, I appreciate when I don't have to resort to a hint. It's so much more satisfying.

I think this was my favorite puzzle.

BTW: zero hints.

You can’t easily google the yellow boxes. They’re all made out of ticky tacky. Use mental induction to figure them out.