didn't work for me at all I'm afraid. the Ulpa group aren't words, Mercury and quicksilver are basically the same thing, Rotor group is done to death. The other group is kind of ok... in isolation, but it doesn't tie in with the rest of the grid, because there's no potential overlaps. 2* feels generous

I liked the HG group. The single words from groups seemed a bit spurious as a group. Can you add palindrome to the rotor group too