The hardest restriction to follow when building a megacrossword is the rule against repeaters. In a 21x21 grid, not having the same word show up twice is just common sense. Most crossword software is programmed not to suggest any words that are already in the grid, and some checks can even warn you if there are any suspiciously similar strings.
Truth to tell, if I didn’t worry at all about repeaters, I could’ve created a “world’s biggest crossword” very easily. All I’d have to do would be to build a string that ends just where it began, like this…
…and then just keep repeating it, like this:
There wouldn’t be a lot of joy to it, and others might not certify it, but repeat that cycle about a million times and you’d have the biggest crossword ever made, no question!
The Ubercross C-Spot is, to my knowledge, the largest crossword that follows all the NYT rules, including the no-repeater rule. And I feel like it’s probably about as big as one can comfortably get while following that rule and not delving into too much obscura. Although a lot depends on how strictly you apply that no-repeater rule.
I’ve seen online discussions of constructors tearing their hair out trying to figure out where the line is…the line that a designer shouldn’t cross. Is it all right for small words to recur in a themeless grid, as in GOING IN along with IN HEAVEN’S NAME? What about if the latter was IN NOMINE PATRIS? Putting in GOING along with GONE is generally a no-no, but what about words that are etymological relatives, like INCREDIBLE and CREDO? What if those etymological relationships are way less obvious, as with AARDVARK and PORCELAIN?
In any case, with the Ubercross Abecedaria, I’m taking a different tack. Between its 125x125 segments, all bets are off, and there are some answers that appear in a large majority of those segments. Within each segment, pure repeaters are discouraged…but very occasionally allowed, in less than 1% of all cases. If it comes down to a choice between putting MINT in the grid twice or crossing -MENT with ELE, I think I should opt to remember that MINT has several unrelated definitions, any one of which is more fun than ELE.
What are the rules behind the rules? The only reason the rules are there is to serve the solver.
Being too loose and free about repetition would not serve the solver, but neither would clinging strictly to a rule that was designed for a very different crossword format. It’s not the only rule I’ve broken in service of this quest, either.
But later for that. There are nine entries that are repeated, once each, within the across and down answers for Ubercross Abecedaria A. That’s well less than 1% of its 4,700 entries, and I call that acceptable. I’m not going to spell out which entries they are…but I will leave you with this visual grid as a set of hints.