There is a deadly skull hidden in one of the nouns, and it's coming to get you.
As the nouns advance, click on the noun hiding the skull to shoot it.
You will know your target noun because it is either an ABSTRACT NOUN (round 1) or a COLLECTIVE NOUN (round 2).
The other nouns are innocent words holding bunches of beautiful flowers. Don't shoot them!
You can only make ONE mistake each round, and you must finish the round before the nouns reach you. Each round gets harder.