As many have mentioned, it seems much more efficient to focus on eliminating letters, which means that the second word should not be very green at all.
Also, since there's only one word a day, I think we can assume that it's chosen manually, and it won't be some archaic anglo-saxon tool for shoeing horses or something, it will be a relatively common word.
I think it's chosen based on a random number generated from the date - but one of the most recent games had the answer "REBUS", which I've never heard or read before. But yeah, the target list has many more common words in it than the list of all possible guesses.
I am pretty sure the list is sequential. If you look at the list in the Javascript code of the game and Ctrl-F today's word, you'll see the previous dates' words are right before it. Here's tomorrow's word (spoiler alert, obv): https://pastebin.com/sfQ7x5ya
It was just a random google result, but we definitely did rebuses in pre-school at least.
The rebus concept is actually a precursor to actual writing, historically speaking. Both in Mesopotamia/Egypt and in the Chinese civilisation, writing developed through a rebus phase. So it's a very natural thing, that's why it's so child friendly.
Why? I mean most pre-schoolers probably play with rebuses, simple crosswords etc. It's just a common concept in the world that most people have come across.
Also, since there's only one word a day, I think we can assume that it's chosen manually, and it won't be some archaic anglo-saxon tool for shoeing horses or something, it will be a relatively common word.