Diagonalization

The real numbers are uncountable and the halting problem is undecidable.

The nice thing about squares is that they have a diagonal. By extension, if you have a square of letters — usually by having obtained n words that are all n letters each — it’s often worth looking at the diagonal of that.

ALIENS
ENOUGH
BUSTER
BLOWUP
HARVEY
BENHUR

Example Puzzles

(add puzzles that use this element here)