I once spend more time than I want to admit constructing the best possible 10-square in Dutch[1]. There are also some other forms that are fun, like cubes[2], or hypercubes. Or using bigrams. Or hexagonal tiles. And so forth.

Finding solutions for big squares/wordlists in reasonable time is actually not a trivial algorithmic problem. Neither is making good wordlists, I ended up creating what is essentially a Dutch version of the Pile[3] just to collect words. Good fun.

[1] https://old.reddit.com/r/thenetherlands/comments/zgr61e/ik_h... [2] https://i.redd.it/a61yuistbkm61.png [3] http://gigacorpus.nl/