Fast Four Word is a clever idea. It's a Wordle-like in which you begin with a four-letter starting word and must enter a new word which changes just a single letter. So if the starting word is AHEM, as it was yesterday, you could change the first letter and enter THEM.
From there, you have 44 seconds to chain together as many new words as you can, with plenty of other twists to make it more challenging.
For a start, if you did replace that A with a T, the T would then be pinned in place so your next word would need to also start with T. So you'd go from THEM to THEY, meaning the T is unpinned but now Y is. It turns out that it's pretty easy to make four-letter words, at first, but soon you'll have exhausted your supply of THEM, THEN, THEY, WHEN and will find yourself stuck down a cul-de-sac, wishing SHEN was a word.
Even if you do get stuck, there are options: you can click the pinned letter in a word to unpin it, opening up your available words in exchange for a four second penalty. You also add time to the clock the first time you use a letter, with more time awarded for less commonly used letters. Now you'll wish ZHEN was a word.
All of which makes Fast Four Words a tough game to play the first time. I spent a substantial portion of my first 44 seconds trying to internalise the rules, and since there's only one puzzle per day, I then had to wait 24 hours to try again. I wish it had a practice mode.
More importantly, it's a compelling enough variant on Wordle that I did come back to try again. I scored 12 on the game for the 28th. You can try to beat my score by playing Fast Four Words in your browser for free.