Clockwords uses words as ammunition. Type any word to fire your lexicon cannon at the advancing enemies. Bonus damage is awarded for using the highlighted selection of letters. Typically these spell a word, so half the challenge is unscrambling that word quickly.
It's well-presented, with some guff about rival inventors and mechanical spy-spiders, and quite addictive. For a word nut like me, anyway. Clockwords [Gabob]