Game Rules

Due to various reasons (such as difficulty of implementation), the rules may differ a little from UNO you've played.

Basic rule

Basic rule is simple: each player has 7 cards initially, when it's your turn, you can play a card (of course you can choose not to play deliberately) if it can be (there is a series of rules to limit which kind of cards can be played), if not, draw a card from deck. The first player to play out all his handcards wins.

Deck

There are totally 108 cards in deck (this is the same with UNO standard rule), among which there are 25 cards each for red, yellow, green and blue color, and 8 cards for wild color (also called black color).

For each color among red, yellow, green and blue, there are 1 card of number 0, 2 cards of number 1 ~ 9, 2 cards of Skip, 2 cards of Reverse and 2 cards of +2 card (Draw card)

For black color, there are 4 cards of color transformation (we call it Wild card if it won't cause confusion) and 4 cards of +4 card (Draw card)

In the game, UI of card consists of two parts: color and text (except that black cards has no color part):

	Number card (0 ~ 9, take 0 for a ref)	Skip	Reverse	+2	Wild	+4
Red	R0	RS	RR	R+2
Yellow	Y0	YS	YR	Y+2
Green	G0	GS	GR	G+2
Blue	B0	BS	BR	B+2
Black					W	+4

Sometimes cards shown in UI are not in the above table (e.g. G, R+4), generally there are two conditions:

• The last played card displayed in the center has only color part (no text part, e.g. G). This is because text part of the card is removed due to some rules (so the next player cannot use Rule of the same text to play a card):
  • The card flipped when game started is a +2, we think it's not reasonable to require the first player to draw 2 cards so the +2 text gets removed and only color is remained to limit the next card (the flipped card wouldn't be black).
  • The last played Skip card has taken effect (i.e. a player has been skipped). For example, A plays a GS, B is skipped, and now to C, the last played card is G.
  • The last played Draw card has taken effect (i.e. a player has taken the punishment of drawing cards). For example, A plays a B+2, B draws 2 cards and now to C, the last played card is B.
• The last played card displayed in the center is a +4 with color part. This is because when playing +4, player needs to specify the next color, which will be attached to the +4 card.

Rules of playing a card

Just like what I've mentioned in UI and Operation Mode Wiki page, the last played card determines what kind of cards the current player can play. To be precise, there are some rules listed below:

• Rule of Uno: Function card (non-Number card) cannot be played as the last one.
• Rule of Skip: If the last played card is Skip, you can only play Skip card.
• Rule of Draw: If the last played card is Draw, you can only play Draw card. Specifically, if the last played card is +4, you can only play +4.
• Rule of the same color: On the premise of not violating above rules, you can play a card which has the same color with the last played card.
• Rule of the same text: On the premise of not violating above rules, you can play a card which has the same text with the last played card.

When the game starts, the card on the top of deck will flipped to be regarded as "the last played card". If a black card is flipped, it will be put to the bottom of deck and flip again. If a +2 card is flipped, its text part will get removed and regarded as a pure-color card without text part.

Other rules

• The punishment of drawing cards can accumulate. For example, A plays a R+2, B plays a G+2, C plays a +4, now if D cannot play a +4, he will draw 8 cards in total.
• After drawing a card you can play it immediately (if it can be played according to the rules), and cannot play any other card. However, if you just took the punishment of drawing cards, you cannot play any card.
• When playing the second-to-last card, UNO will be yelled out automatically (UNO text in UI center)
• +4 card cannot be queried.