wordslicer.com
After having pressed "learn to play" I got to the bit "Give it a try and form the word E N D" but the UI was frozen . I then selected "Exit how to play" but that left the URL unchanged so I was sent back to the start of the tour.
This is on Firefox on Windows.
I just went and tried to do the same thing again and it worked as expected. This may be due to you having made changes but if you haven't there was something else I was going to mention which may be relevant. When I started the 'How to play' section on the first occasion I got the 'Would you like cookies with that?' dialog which I responded to before starting the 'How to play'. When the 'How to play' behaved oddly I did just wonder whether it was somehow related to the cookies dialog. The reason I mention this is because having gone back to try it today I was, understandably, not prompted by the cookies dialog so (just maybe) the 'how to play' getting stuck is related to the cookies dialog ? Just an idea.
What dictionary are you using? I tried a couple of words like 'acing' and 'awing' that should work?
On the words: Word Slicer focuses on base or dictionary forms. The list includes common nouns (like river), verbs (like dance), and adjectives (like bright). You’ll find wide but not wider, for example — which is why words like acing or awing don’t register.