Also, the mallets and balls were not exactly being tortured to death. There is no indication in the passage that the animals were anything other than puzzled and perhaps annoyed:
"The chief difficulty Alice found at first was in managing her flamingo: she succeeded in getting its body tucked away, comfortably enough, under her arm, with its legs hanging down, but generally, just as she had got its neck nicely straightened out, and was going to give the hedgehog a blow with its head, it would twist itself round and look up in her face, with such a puzzled expression that she could not help bursting out laughing: and when she had got its head down, and was going to begin again, it was very provoking to find that the hedgehog had unrolled itself, and was in the act of crawling away..."
-- Alice in Wonderland, ch. VIII
snip...I don't think that the Red Queen's croquet game is really an apt metaphor for cruelty... as the illustration posted at the top of the thread indicates, Alice herself didn't have any problem taking part in the game
It doesn't take much imagination to envision what would happen to the head, neck, and bill of a flamingo were it to be used as a 'club'. Lewis Carroll expected us to make use of our imaginations to 'fill in the blanks'.
As for Alice taking part in the game......naturally she did. She found herself transported to a world of insanity and she realized that she had to make the best of her situation while simultaneously not losing her own sanity.
The cruelty of the game is its being wihout end.