I was surpirsed this worked as it was made 10+ years ago and it's no longer on the shop unless you already have it downloaded or you searched for it on Google.

In terms of gameplay, you can challenge people that don't say UNO, but that doesn't matter. At least for the Adventure/Story Mode, challenging and not challenging not saying UNO doesn't make a difference. The AI will always let you win and will ALWAYS draw a card when they only have one left, even if they selected a color with their second to last card.

Fun since it's still UNO, but no strategy required and time waster as you'll always win.