As he says, none of this is written in stone. He has an interesting style. Grammarians and editors will love this site. If you care at all about English, its rules, and its usage, you will find that this site's analyses are educational and thought-provoking. A worthwhile site if you love the English language.
Archives are available online.
All of these sites have been tested on our computers at home on an Apple IMAC and a G3 laptop. Word Invasion Letters keep dropping from the sky, threatening the city. This one is just a demo but good practice. It uses the same four sentences over and over but good speed practice. Gives your score and the number of errors.