"UNO! Mobile" is a mobile version of the card game "UNO" created by Mattel163 Limited (a joint venture of the American company Mattel and the Chinese internet giant NetEase) in 2019 for mobile iOS and Android systems. The original physical version of the game was created by Merle Robbins in 1971 and is conceptually similar to "Macao", and a special deck of cards is used to play "UNO". In addition to the original version, there are many variations and specific rules of this game using the above deck. There can be from 2 to 10 players - it is also possible to divide into 2-person teams. At the beginning of the game, 7 cards are dealt to each player and one of the deck is placed in the center. The game is started by the person to the left of the dealer. The player must match their card by number, color or symbol to the face-up card. If the player does not have any card that matches the face-up one, they must draw a card from the deck. If the drawn card matches the one that is revealed, the player can add it in the same turn. If not, the next player has a turn. There is no obligation to add cards. The deck also includes special cards such as Stop, Change Direction, Take Two, Choose a Color + Take Four, Choose a Color. The Stop, Change Direction, Take Two cards can be placed on a given color card; however, the Choose a Color + Take Four cards can be placed on any card. If a player is left with one card in their hand, they must shout "UNO!" (which means "One!"). If they do not do this, they must draw 2 cards, but only if at least one player notices their oversight before the player with one card corrects themselves. The first player to get rid of all their cards wins. The goal of the game is to get rid of all the cards in their deck. The time limit is 3 minutes to play (there is no time limit in the physical version of the game).