UNO on Nspire!
Press left and right to choose the card.
Press enter to use the card.
Press esc to draw a card, if you has drawn one, that means you give up the turn.
Press 7/9 when deciding to (not to) challenge another one's +4 card.
When you find some had just one card without yell "UNO!", press the number of his name to make him draw 2 cards!
The last and the most important thing, when you will left just one card in your hand. Don't forget to press 5 to yell "UNO!".
Specially thanks for another UNO's programmmer @Nick , I used the colors and some marks of his game.