[quantumtremor]

In particular, a good challenge is the 2-state solution. Decrease the number of states to 2 and try figuring out the rules (toggle "Instructions") that make the 2-state Busy Beaver. 1-state is somewhat trivial, 3-state isn't really possible by hand unless you have a lot of time.

[brudgers]

Interesting. Probably would be helpful to describe the Busy Beaver problem. https://en.wikipedia.org/wiki/Busy_beaver