Let's Play UNO!

You may only cast this card if each player has at
least 3 cards in their hand.
Whenever a player plays the last card in his or her
hand that player must shout "UNO!"
If another player shouts "UNO!" before that
player does, the card is not cast and that player
must draw 2 cards.
If a player has no cards in his or her hand at the beginning of an end step, they win the game.