You can play a Draw 4 card in Uno when you don't have a matching color or number card to play.
No, it is not possible to challenge a Draw 4 card in Uno.
No, you cannot put a Draw 4 card on top of a Draw 2 card in Uno.
No, you cannot put a Draw 2 card on top of a Draw 4 card in Uno.
No, you cannot put a Draw 4 card on top of a Draw 2 card in Uno.
No, you cannot stack a Draw 2 card on top of a Draw 4 card in Uno.
No, you cannot stack a Draw 4 card on top of a Draw 2 card in Uno.
No, you cannot put a wild card on a Draw 4 card in Uno.
No, you cannot end a game of Uno with a Draw 4 card.
In Uno, when a Draw 4 card is played, the next player must draw 4 cards and forfeit their turn. The player who played the Draw 4 card gets to choose the color that play continues with.
No, you cannot stack a Draw 4 card on top of a Draw 2 card in the game of Uno.
No, you cannot put a Skip card on top of a Draw 4 card in Uno.
In Uno, when a player plays a Wild Card Draw 4, the next player must draw 4 cards from the deck. The player who played the Wild Card Draw 4 gets to choose the color that play continues with.