Matt Leacock just posted his difficulty ideal on BGG.

Design the game such that:
if a group of people appropriately self-selects a well-defined difficulty setting,
that their odds of success will be about 50/50,

I have one of these near where I live. Buying directly from local suppliers is best, of course, but the discovery process can be painful.

In that regard, these stores are, at minimum, really great for finding local food near you! They also tend to have some nonstandard stuff in general.

EMMA is a NYC-based worker-owned technology cooperative. We develop software for clients in the video game and interactive media art industries.